There are a number of ways to find truth.  It depends on "Proof."  There are a number of ways to arrive at truth through proof.

1. Analytical or mathematical truth using a proven formula.  Remember the Pythagorean Theorem.
2. Logical truth.  If all birds have feathers, and a robin is a bird--then robins have feathers.
3. Sensory truth.  Touch, taste, sight, sound, smell.  Touch a hot stove and you will get burned.
4. Historical truth.  Established on a preponderance of evidence.  Not as reliable as other truths.
5. Elimination truth. I use this every morning when I solve the Sudoku puzzle.
6. Substitution truth.
7. Convergence truth.  When I taught Calculus, we were able to find the slope at a point on a curve.  You remember that a curve has no slope, but using "limits", you can find it at any point.  It goes something like this: if I step toward you and split the difference between us, then do it again and again, no matter how often I do that I will never really reach you.  But for all practical purposes the distance between us approaches zero.  Or, the "limit" of the distance between us approaches zero.
I love Calculus. But then, I love logic and "proofs."  I guess that's why I am a mathematician.

The proof that Jesus existed, that he lived, taught, was crucified, and rose again comes to us from a preponderance of evidence.  Historical evidence: gathered for around 5000 years.  Elimination truth: no one else has ever come close statistically to fulfilling 72 prophecies except Jesus.  Etc., etc.  If you carry that out to 72 places, not that many people have ever lived.  It is statistically amazing that Jesus met the qualifications.

But after you have accepted Him as the truth: God in man, the Son of God, or as Thomas said: "My Lord, and my God,"  something happens within.  You are changed.  His Spirit takes up residence with a broom and begins to sweep out all of that bitterness, hate, jealousy, spite, anger, and on and on.  You are never the same.  Peace begins to take over.  It is experiential truth.

I am not the same.  He has changed me.  Thank God.