"I challenge to present the hard PROOF for your Christian CLAIM that Jesus Christ is the truth, etc! (John 14:6)"
And, I thought I'd share my response. Would love to hear your thoughts--where I went right, where I (gulp!) went wrong, and how you would respond to the same challenge.
There are three reasons why you are asking me this question.
One, that you have a sincere, seeking heart, looking for reassurance of what you hope to be true—that Jesus Christ is the way, the truth and the life. If this is the case, it is my prayer that my answer will give you reassurance and will invite you into a relationship with him.
Two, that you are a fellow Christian, inviting me to the challenge in 1 Peter 3:15, "Always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have. But do this with gentleness and respect, keeping a clear conscience, so that those who speak maliciously against your good behavior in Christ may be ashamed of their slander."
Three, that you are one of those from 1 Peter 3:15, seeking to speak maliciously.
That said...here's my answer!
I could bring your attention to the fact that, as his life is recorded in the Gospels of Matthew, Mark, Luke and John, Jesus fulfills the prophecies of a thousand years before, recorded in the books of Isaiah and Daniel. I could tell you that, were the promises of his power not true, we would not have seen this new “religion” sweep through the world and endure—unchanged in its message—more than two thousand years later. I could go on with the statistics of his resurrected appearances being the best documented historical even of its era.
But, really, the best proof I have is my own life. I can tell you that I never live a day without hope. I can tell you that, even with the tragic death of my brother, I had (and still have) an unyielding sense of peace and comfort because of the promise of eternal life with Jesus Christ that both he and I share. And I can tell you that I see miracles in my life every day—prayers answered before I even knew to pray them. I look at the troubles in this world, and I have no fear because Jesus told us there would be troubles in this world. Things may be awful sometimes, but they are not out of his control. I have accomplished things in my life that I never could have accomplished in my own power—including answering this email, because after my first flash of defensiveness, I took a deep breath, hit “reply” and asked Jesus, through the Holy Spirit, to reply through me.
You referenced John 14:6 in your email. I invite you to the next verse—If you really knew me, you would know my Father as well. From now on you do know him and have seen him. (John 14:7) That’s all the proof I can offer—the Jesus of the scriptures, and the Jesus of my life. One and the same.