“He that had ascended unto it [heaven] is now come”

Followers of the Gospel, behold the gates of heaven are flung open. He that had ascended unto it is now come. Give ear to His voice calling aloud over land and sea, announcing to all mankind the advent of this Revelation—a Revelation through the agency of which the Tongue of Grandeur is now proclaiming: ‘Lo, the sacred Pledge hath been fulfilled, for He, the Promised One, is come!’ 

- Baha’u’llah  (Quoted by Shoghi Effendi in a letter dated February 8, 1934; ‘The Dispensation of Baha’u’llah’)

Those who rejected Christ when He came unto them

Consider those who rejected the Spirit [Christ] when He came unto them with manifest dominion. How numerous the Pharisees who had secluded themselves in synagogues in His name, lamenting over their separation from Him, and yet when the portals of reunion were flung open and the divine Luminary shone resplendent from the Dayspring of Beauty, they disbelieved in God, the Exalted, the Mighty. They failed to attain His presence, notwithstanding that His advent had been promised them in the Book of Isaiah as well as in the Books of the Prophets and the Messengers. No one from among them turned his face towards the Dayspring of divine bounty except such as were destitute of any power amongst men. And yet, today, every man endowed with power and invested with sovereignty prideth himself on His Name. Moreover, call thou to mind the one who sentenced Jesus to death. He was the most learned of his age in his own country, whilst he who was only a fisherman believed in Him. Take good heed and be of them that observe the warning. 
- Baha’u’llah  (Lawh-i-Aqdas (The Most Holy Tablet) [Sometimes referred to as Tablet to the Christians],‘Tablets of Baha’u’llah Revealed after the Kitab-i-Aqdas’)

The Tree of Life

O leaf upon the Tree of Life! The Tree of Life, of which mention is made in the Bible, is Bahá'u'lláh, and the daughters of the Kingdom are the leaves upon that blessed Tree. Then thank thou God that thou hast become related to that Tree, and that thou art flourishing, tender and fresh.

The gates of the Kingdom are opened wide, and every favoured soul is seated at the banquet table of the Lord, receiving his portion of that heavenly feast. Praised be God, thou too art present at this table, taking thy share of the bountiful food of heaven. Thou art serving the Kingdom, and art well acquainted with the sweet savours of the Abha Paradise.

Then strive thou with all thy might to guide the people, and eat thou of the bread that hath come down from heaven. For this is the meaning of Christ's words: 'I am the living bread which came down from heaven ... he that eateth of this bread shall live forever.'[John 6:51, 58] 
- ‘Abdu'l-Baha  (Selections from the Writings of Abdu'l-Baha)

The meaning of the “resurrection of the body of Christ three days subsequent to His departure”

As to the resurrection of the body of Christ three days subsequent to His departure: This signifies the divine teachings and spiritual religion of His Holiness Christ, which constitute His spiritual body, which is living and perpetual forevermore.

By the "three days' of His death is meant that after the great martyrdom, the penetration of the divine teachings and the spread of the spiritual law became relaxed on account of the crucifixion of Christ. For the disciples were somewhat troubled by the violence of divine tests. But when they become firm, that divine spirit resurrected and that body - which signifies the divine word - arose.

Likewise the address of the angels to the people of Galilee, "That this Christ will return in the same way and that He will descend from heaven," is a spiritual address. For when Christ appeared, he came from heaven, although He was outwardly born from the womb of Mary. For He said: "No man hath ascended up to heaven, but he that came down from heaven."

He said: "I came down from heaven and likewise will go to heaven." By "Heaven" is not meant this infinite phenomenal space, but "heaven" signifies the world of the divine kingdom which is the supreme station and seat of the Sun of Truth. 
- ‘Abdu’l-Baha  (‘Tablets of Abdul-Baha Abbas", vol.1; compilation ‘Resurrection of Jesus Christ’, prepared by the Research Department of the Universal House of Justice)

“The disciples of Christ taught His Faith with the language of the Kingdom”

The disciples of Christ taught His Faith with the language of the Kingdom. That language conformeth to all languages, for it consisteth of celestial meanings and divine mysteries. For the one who becometh conversant with that language the realities and secrets of creation stand unveiled before him. Divine truths are common to all languages. The Holy Spirit, therefore, taught the disciples the language of the Kingdom, and they thus were able to converse with the people of all nations. Whenever they spoke to those of other nations of the world, it was as if they conversed in their tongues. The well-known and outstanding languages of the world number about a thousand. It was necessary for the disciples to have written the Gospels in at least one of the languages of other nations. Thus, as it is known, the Gospels were written only in Hebrew and Greek, and not even in the language of the Romans, although it was at the time the official language. As the disciples were not well-versed in it, the Gospels were not written in that language. 
- ‘Abdu’l-Baha  (From a Tablet; Compilation on ‘The Bible: Extracts on the Old and New Testaments’, prepared by the Research Department of the Universal House of Justice )

The creation of “heaven and earth in six days” …

...What is intended by the creation of heaven and earth in six days is a spiritual creation and a divine day, as prior to the creation of this heaven and earth there were no days and nights. 
- ‘Abdu’l-Baha  (From a Tablet; Compilation on ‘The Bible: Extracts on the Old and New Testaments’, prepared by the Research Department of the Universal House of Justice)