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')