Simply put, I believe that Jesus existed because Baha'u'llah testified of Jesus:
Referring to Jesus as the Son of Man, Baha’u’llah wrote:
“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.”
Gleanings From the Writings of Bahá’u’lláh, pp. 85-86
Yes, either I believe that Jesus existed or not, but after that I can choose to believe what I believe about Jesus. I do not have to believe everything that was recorded on the NT and I do not have to interpret it as you do.
Even if nobody from the first few centuries managed to prove it to be a fraud that does not mean that everything recorded in the NT is a fact. No, it is not as simple as either the NT was a fraud or not. Below is the Baha'i position on the Bible:
The Bahá'í viewpoint proposed by this essay has been established as follows: The Bible is a reliable source of Divine guidance and salvation, and rightly regarded as a sacred and holy book. However, as a collection of the writings of independent and human authors, it is not necessarily historically accurate. Nor can the words of its writers, although inspired, be strictly defined as 'The Word of God' in the way the original words of Moses and Jesus could have been. Instead there is an area of continuing interest for Bahá'í scholars, possibly involving the creation of new categories for defining authoritative religious literature.
A Baháí View of the Bible
The Bahá'ís believe that God's Revelation is under His care and protection and that the essence, or essential elements, of what His Manifestations intended to convey has been recorded and preserved in Their Holy Books. However, as the sayings of the ancient Prophets were written down some time later, we cannot categorically state, as we do in the case of the Writings of Bahá'u'lláh, that the words and phrases attributed to Them are Their exact words
(9 August 1984 to an individual believer)
The Bible: Extracts on the Old and New Testaments
In studying the Bible Bahá'ís must bear two principles in mind. The first is that many passages in Sacred Scriptures are intended to be taken metaphorically, not literally, and some of the paradoxes and apparent contradictions which appear are intended to indicate this. The second is the fact that the text of the early Scriptures, such as the Bible, is not wholly authentic.
(28 May 1984 to an individual believer)
The Bahá'ís believe what is in the Bible to be true in substance. This does not mean that every word recorded in that Book is to be taken literally and treated as the authentic saying of a Prophet....
The Bahá'ís believe that God's Revelation is under His care and protection and that the essence, or essential elements, of what His Manifestations intended to convey has been recorded and preserved in Their Holy Books. However, as the sayings of the ancient Prophets were written down some time later, we cannot categorically state, as we do in the case of the Writings of Bahá'u'lláh, that the words and phrases attributed to Them are Their exact words
(9 August 1984 to an individual believer)
The Bible: Extracts on the Old and New Testaments