The meaning of the Messiah's words “Verily the Son is in the Father, and the Father is in the Son.'[John 14:10]

Know thou that the Divine Essence, which is called the Invisible of the Invisibles, never to be described, beyond the reach of mind -- is sanctified above any mention, any definition or hint or allusion, any acclamation or praise. In the sense that It is that It is, the intellect can never grasp It, and the soul seeking knowledge of It is but a wanderer in the desert, and far astray. 'No vision taketh in Him, but He taketh in all vision: He is the Subtile, the All-Informed.'[1]

When, however, thou dost contemplate the innermost essence of all things, and the individuality of each, thou wilt behold the signs of thy Lord's mercy in every created thing, and see the spreading rays of His Names and Attributes throughout all the realm of being, with evidences which none will deny save the froward and the unaware. Then wilt thou observe that the universe is a scroll that discloseth His hidden secrets, which are preserved in the well-guarded Tablet. And not an atom of all the atoms in existence, not a creature from amongst the creatures but speaketh His praise and telleth of His attributes and names, revealeth the glory of His might and guideth to His oneness and His mercy: and none will gainsay this who hath ears to hear, eyes to see, and a mind that is sound.

Prayer Christ said while being hanged on the cross

Remind them of these words and say unto them: 'Verily did the Pharisees rise up against Messiah, despite the bright beauty of His face and all His comeliness, and they cried out that He was not Messiah [Masih] but a monster [Masikh], because He had claimed to be Almighty God, the sovereign Lord of all, and told them, 'I am God's Son, and verily in the inmost being of His only Son, His mighty Ward, clearly revealed with all His attributes, all His perfections, standeth the Father.' This, they said, was open blasphemy and slander against the Lord according to the clear and irrefutable texts of the Old Testament. Therefore they passed the sentence upon Him, decreeing that His blood be shed, and they hanged Him on the cross, where He cried out, 'O My beloved Lord, how long wilt Thou abandon Me to them? Lift Me up unto Thee, shelter Me close to Thee, make Me a dwelling by Thy throne of glory. Verily art Thou the Answerer of prayers, and Thou art the Clement, the Merciful. O My Lord! Verily this world with all its vastness can no longer contain Me, and I love this cross, out of love for Thy beauty, and yearning for Thy realm on high, and because of this fire, fanned by the gusts of Thy holiness, aflame within My heart. Help me, O Lord, to ascend unto Thee, sustain Me that I may reach unto Thy sacred Threshold, O My loving Lord! Verily Thou art the Merciful, the Possessor of great bounty! Verily Thou art the Generous! Verily Thou art the Compassionate! Verily Thou art the All-Knowing! There is none other God save Thee, the Mighty, the Powerful!' 
- ‘Abdu'l-Baha  ('Selections from the Writings of ‘Abdu'l-Baha')

"O would that all were truly Christian!"

Thou didst begin thy letter with a blessed phrase, saying: 'I am a Christian.' O would that all were truly Christian! It is easy to be a Christian on the tongue, but hard to be a true one. Today some five hundred million souls are Christian, but the real Christian is very rare: he is that soul from whose comely face there shineth the splendour of Christ, and who showeth forth the perfections of the Kingdom; this is a matter of great moment, for to be a Christian is to embody every excellence there is. I hope that thou, too, shalt become a true Christian. Praise thou God that at last, through the divine teachings, thou hast obtained both sight and insight to the highest degree, and hast become firmly rooted in certitude and faith. It is my hope that others as well will achieve illumined eyes and hearing ears, and attain to everlasting life: that these many rivers, each flowing along in diverse and separated beds, will find their way back to the circumambient sea, and merge together and rise up in a single wave of surging oneness; that the unity of truth, through the power of God, will make these illusory differences to vanish away. This is the one essential: for if unity be gained, all other problems will disappear of themselves. 
- ‘Abdu'l-Baha  ('Selections from the Writings of ‘Abdu'l-Baha')

Three days after His crucifixion “the disciples became assured and steadfast, … began to serve the Cause of Christ” and as a result “the Reality of Christ became resplendent and His bounty appeared”

...The Cause of Christ was like a lifeless body; and when after three days the disciples became assured and steadfast, and began to serve the Cause of Christ, and resolved to spread the divine teachings, putting His counsels into practice, and arising to serve Him, the Reality of Christ became resplendent and His bounty appeared; His religion found life; His teachings and His admonitions became evident and visible. In other words, the Cause of Christ was like a lifeless body until the life and the bounty of the Holy Spirit surrounded it.

Such is the meaning of the resurrection of Christ, and this was a true resurrection....
- ‘Abdu’l-Baha  (‘Some Answered Questions')

Meeting of Christ with the apostles after His crucifixion

...Thou hast written concerning the meeting of His Highness Christ after the crucifixion and that some of the apostles perceived Him but did not recognize Him; but that they did recognize Him after the breaking of bread.

Know thou that the Messianic Spirit and the outpouring of the Holy Spirit is always manifest, but capacity and ability (to receive it) is more in some and less in others. After the crucifixion the apostles had not in the beginning the capacity and ability of witnessing the Messianic reality. For they were agitated. But when they found firmness and steadfastness, their inner sight became opened, and they saw the reality of the Messiah as manifest. For the body of Christ was crucified and vanished, but the Spirit of Christ is always pouring upon the contingent world, and is manifest before the insight of the people of assurance. 
- ‘Abdu’l-Baha  (Tablets of Abdul-Baha, Vol. 1)

The version of the “heavenly Gospel” currently in existence is the “genuine text”

We have also heard a number of the foolish of the earth assert that the genuine text of the heavenly Gospel doth not exist amongst the Christians, that it hath ascended unto heaven. How grievously they have erred! How oblivious of the fact that such a statement imputeth the gravest injustice and tyranny to a gracious and loving Providence! 
- Baha’u’llah  ('The Book of Certitude')

Apostles were like "Letters" Christ was the "the essence of the Word Itself"

The Apostles of Christ were even as Letters, and Christ was the essence of the Word Itself; and the meaning of the Word, which is grace everlasting, cast a splendor on those Letters. Again, since the Letter is a member of the Word, it therefore, in its inner meaning, is consonant with the Word.” 
- ‘Abdu’l-Baha  ('Selections from the Writings of ‘Abdu’l-Baha')

General Baha’i attitude towards Christianity

As to the position of Christianity, let it be stated without any hesitation or equivocation that its Divine origin is unconditionally acknowledged, that the Sonship and Divinity of Jesus Christ are fearlessly asserted, that the Divine inspiration of the Gospel is fully recognized, that the reality of the mystery of the Immaculacy of the Virgin Mary is confessed, and the primacy of Peter, the Prince of the Apostles, is upheld and defended. 
- Shoghi Effendi  (The Promised Day is Come')

Baha’u’llah exalts the station of Jesus, His mother and Peter

The Founder of the Christian Faith is designated by Bahá'u'lláh as the "Spirit of God," is proclaimed as the One Who "appeared out of the breath of the Holy Ghost," and is even extolled as the "Essence of the Spirit." His mother is described as "that veiled and immortal, that most beauteous, countenance," and the station of her Son eulogized as a "station which hath been exalted above the imaginings of all that dwell on earth," whilst Peter is recognized as one whom God has caused "the mysteries of wisdom and of utterance to flow out of his mouth." 
- Shoghi Effendi  ('The Promised Day is Come')

The effect of Jesus on the world

Know thou that when the Son of Man yielded up His breath to God, the whole creation wept with a great weeping. By sacrificing Himself, however, a fresh capacity was infused into all created things. Its evidences, as witnessed in all the peoples of the earth, are now manifest before thee. The deepest wisdom which the sages have uttered, the profoundest learning which any mind hath unfolded, the arts which the ablest hands have produced, the influence exerted by the most potent of rulers, are but manifestations of the quickening power released by His transcendent, His all-pervasive and resplendent Spirit. We testify that when He came into the world, He shed the splendor of His glory upon all created things. Through Him the leper recovered from the leprosy of perversity and ignorance. Through Him the unchaste and wayward were healed. Through His power, born of Almighty God, the eyes of the blind were opened and the soul of the sinner sanctified.... He it is Who purified the world. Blessed is the man who, with a face beaming with light, hath turned towards Him. 
- Baha’u’llah  (Quoted by Shoghi Effendi in 'The Promised Day is Come')

Resurrection of Jesus

We do not believe that there was a bodily resurrection after the crucifixion of Christ, but that there was a time after His ascension when His disciples perceived spiritually His true greatness and realized He was eternal in being. This is what has been reported symbolically in the New Testament and been misunderstood. His eating with His disciples after resurrection is the same thing. 
- Shoghi Effendi  (From a letter written on behalf of Shoghi Effendi, ‘High Endeavours - Messages to Alaska’)

Process through which the Kingdom promised by Christ will be established on earth

His [Baha’u’llah’s] purpose, far from belittling the station of the Prophets gone before Him or of whittling down their teachings, is to restate the basic truths which these teachings enshrine in a manner that would conform to the needs, and be in consonance with the capacity, and be applicable to the problems, the ills and perplexities, of the age in which we live. His mission is to proclaim that the ages of the infancy and of the childhood of the human race are past, that the convulsions associated with the present stage of its adolescence are slowly and painfully preparing it to attain the stage of manhood, and are heralding the approach of that Age of Ages when swords will be beaten into plowshares, when the Kingdom promised by Jesus Christ will have been established, and the peace of the planet definitely and permanently ensured. Nor does Bahá'u'lláh claim finality for His own Revelation, but rather stipulates that a fuller measure of the truth He has been commissioned by the Almighty to vouchsafe to humanity, at so critical a juncture in its fortunes, must needs be disclosed at future stages in the constant and limitless evolution of mankind. 
- Shoghi Effendi  ('Summary Statement - 1947, Special UN Committee on Palestine')

The miracle associated with the birth of Jesus

What science calls a virgin birth we do not associate with that of Jesus Christ, which we believe to have been a miracle and a sign of His Prophethood. In this matter we are in entire agreement with the most orthodox church views. 
- Shoghi Effendi  (From a letter written on behalf of Shoghi Effendi, ‘High Endeavours - Messages to Alaska’)

Baha’u’llah addresses a most weighty Epistle to Pope Pius IX

To Pope Pius IX, the undisputed head of the most powerful Church in Christendom, possessor of both temporal and spiritual authority, He, a Prisoner in the army barracks of the penal-colony of 'Akká, addressed a most weighty Epistle, in which He announces that "He Who is the Lord of Lords is come overshadowed with clouds," and that "the Word which the Son concealed is made manifest." He, moreover, warns him not to dispute with Him even as the Pharisees of old disputed with Jesus Christ; bids him leave his palaces unto such as desire them, "sell all the embellished ornaments" in his possession, "expend them in the path of God," abandon his kingdom unto the kings, "arise ... amidst the peoples of the earth," and summon them to His Faith. Regarding him as one of the suns of the heaven of God's names, He cautions him to guard himself lest "darkness spread its veils" over him; calls upon him to "exhort the kings" to "deal equitably with men"; and counsels him to walk in the footsteps of his Lord, and follow His example. 
- Shoghi Effendi  ('God Passes By')

Some references to ‘Akka (Acre), the prison city in Palestine (currently Israel) where Baha’u’llah was exiled in 1868

Akká, itself, flanked by the "glory of Lebanon," and lying in full view of the "splendor of Carmel," at the foot of the hills which enclose the home of Jesus Christ Himself, had been described by David as "the Strong City," designated by Hosea as "a door of hope," and alluded to by Ezekiel as "the gate that looketh towards the East," whereunto "the glory of the God of Israel came from the way of the East," His voice "like a noise of many waters." 
- Shoghi Effendi  ('God Passes By')

Baha’u’llah’s shrine is at Bahji, the property located north-east of the city of Acre. It is a place of pilgrimage for Baha’is worldwide and the point to which Baha'is turn in prayer.

Some references about Baha’u’llah by Christ and His Apostles

To Him Jesus Christ had referred as the "Prince of this world," as the "Comforter" Who will "reprove the world of sin, and of righteousness, and of judgment," as the "Spirit of Truth" Who "will guide you into all truth," Who "shall not speak of Himself, but whatsoever He shall hear, that shall He speak," as the "Lord of the Vineyard," and as the "Son of Man" Who "shall come in the glory of His Father" "in the clouds of heaven with power and great glory," with "all the holy angels" about Him, and "all nations" gathered before His throne. To Him the Author of the Apocalypse had alluded as the "Glory of God," as "Alpha and Omega," "the Beginning and the End," "the First and the Last." Identifying His Revelation with the "third woe," he, moreover, had extolled His Law as "a new heaven and a new earth," as the "Tabernacle of God," as the "Holy City," as the "New Jerusalem, coming down from God out of heaven, prepared as a bride adorned for her husband." To His Day Jesus Christ Himself had referred as "the regeneration when the Son of Man shall sit in the throne of His glory." To the hour of His advent St. Paul had alluded as the hour of the "last trump," the "trump of God," whilst St. Peter had spoken of it as the "Day of God, wherein the heavens being on fire shall be dissolved, and the elements shall melt with fervent heat." His Day he, furthermore, had described as "the times of refreshing," "the times of restitution of all things, which God hath spoken by the mouth of all His holy Prophets since the world began." 
- Shoghi Effendi ('God Passes By')

The Báb was the “Return of John the Baptist”; He exhibited the “radiance of Jesus”

The Báb was “the ‘Qá'im’ (He Who ariseth) promised to the Shí'ahs, the ‘Mihdi’ (One Who is guided) awaited by the Sunnis, the ‘Return of John the Baptist’ expected by the Christians, the ‘Ushidar-Mah’ referred to in the Zoroastrian scriptures, the ‘Return of Elijah’ anticipated by the Jews, Whose Revelation was to show forth ‘the signs and tokens of all the Prophets’, Who was to ‘manifest the perfection of Moses, the radiance of Jesus and the patience of Job’ …” He was the ‘Second Woe,’ spoken of in the Apocalypse of St. John the Divine …” - Shoghi Effendi  ('God Passes By')

Fulfillment of the reference from the Revelation of St. John the Divine concerning the appearance of one of the two "Witnesses" into whom, ere the "second woe is past," the "spirit of life from God" must enter

Quddus, immortalized by Him as Ismu'llahi'l-Akhir (the Last Name of God); on whom Bahá'u'lláh's Tablet of Kullu't-Ta'am later conferred the sublime appellation of Nuqtiy-i-Ukhra (the Last Point); whom He elevated, in another Tablet, to a rank second to none except that of the Herald of His Revelation; whom He identifies, in still another Tablet, with one of the "Messengers charged with imposture" mentioned in the Qur'án; whom the Persian Bayan extolled as that fellow-pilgrim round whom mirrors to the number of eight Vahids revolve; on whose "detachment and the sincerity of whose devotion to God's will God prideth Himself amidst the Concourse on high;" whom 'Abdu'l-Bahá designated as the "Moon of Guidance;" and whose appearance the Revelation of St. John the Divine anticipated as one of the two "Witnesses" into whom, ere the "second woe is past," the "spirit of life from God" must enter -- such a man had, in the full bloom of his youth, suffered, in the Sabzih-Maydan of Barfurush, a death which even Jesus Christ, as attested by Bahá'u'lláh, had not faced in the hour of His greatest agony. 
- Shoghi Effendi  (God Passes By')

Explanations of specific passages in the Bible: Revelation: 12th chapter of Ecclesiastes

As to thy question concerning the 12th chapter of Ecclesiastes: This is prophecy regarding the coming of Jesus in that book, the signs and marks of which were fulfilled with the appearance of the Promised One of the Bible ["Bible" signifies the Old Testament; "Gospel" signifies the New Testament.]; but since the Jews did not understand the meaning thereof, so they denied Jesus and -- God forbid! -- said that He was the deformed (Antichrist). Then it is said by Jesus in the Gospel, that similar signs would appear in the "last day" -- or in other words -- in the day when Christ will come the second time in this world.

The interpretation of these statements is mentioned in the clearest manner and with the most wonderful proofs in the Book of Iqan. 
- ‘Abdu'l-Baha  (Tablets of Abdu'l-Baha vol. 1)

Explanation of Specific Passages in the Bible: Revelation: Chapter 21 verses 21 & 17

          
Thou hast asked in regard to the 10th verse of the 21st chapter of Revelation and to the 17th verse: Know that the firmament of the bright sun of the world of possibilities is divided into twelve sections, according to mathematical principles, which are called the twelve constellations; likewise, the Sun of Truth manifests and pours forth His bounty in twelve constellations of holiness. By these constellations are meant holy souls who are the manifestations of purity and the dawning-points of the lights of Unity. Observe that in the day of His Holiness the Speaker of God (Moses), there were twelve holy souls who were the leaders of the Truth. In like manner, in the cycle of His Holiness the Spirit (Jesus Christ), note that there were twelve apostles under the shadow of the light of the Most High, and the Sun of Truth was manifested through those bright dawning-places like unto the phenomenal sun. Likewise, in the time of His Holiness Mohammed, consider that there were twelve dawning points of holiness who were the manifestations of confirmation. Such is the case.