[1] That which was from the beginning, which we have heard, which we have seen with our eyes, which we looked upon and have touched with our hands, concerning the word of life—[2] the life was made manifest, and we have seen it, and testify to it and proclaim to you the eternal life, which was with the Father and was made manifest to us—[3] that which we have seen and heard we proclaim also to you, so that you too may have fellowship with us; and indeed our fellowship is with the Father and with his Son Jesus Christ. 1 John 1:1–3
There are many verses in the New Testament that attest to the truthfulness of its claims. There are multiple accounts of people who claimed to be eyewitnesses to the events in the New Testament, including those who claimed to have seen Jesus after he was resurrected. Archeology corroborates many of the cultural and historical details that are mentioned in the Biblical texts. Early church fathers accepted the writings that would become the New Testament as true, verifying their early acceptance, and the message is remarkably similar across the texts which were written by different authors. The New Testament also fulfilled many of the prophecies of the Old Testament. Perhaps most telling are the many apostles who were persecuted and executed for their beliefs, suggesting that they really believed the message they were spreading.
Also adding weight to the argument that the New Testament is true is the impact that Christianity has had on the cultures and societies around the world, as well as the impact it has had on moral and ethical teachings in the world even today. Christianity’s rapid growth from something like 20 people at the time of Jesus’s death to around 10% of the population of the Roman Empire (30 million people) by 300 AD, in spite of the fact that it was often very dangerous to be a Christian, testifies to its truth as well.
Isn’t it reasonable to believe that Christianity is true?