Imo, the only way to KNOW is to ask the One who was there... Christ. T
But you can use all four things I mentioned (and more if you can think of more) to determine truth of something/someone.
As for me, I recognized truth in the teachings of Christ. I saw the truth of them in my own life. I believed in Him from what He taught/from His message... and I also put faith in Him and what He taught. Then from learning ABOUT Him, He does invite us to move forward and go TO Him... for truth, for life. (not just search the scriptures, but go to Him... as He IS alive and here) This is not so easy to do, because we are 'sight' creatures. We need (most of us for the most part) to see, touch, hear, smell, taste... something in order to understand it. We rely very much on these physical senses; and the spirit is not a physical sense. So for many (most, I would guess, especially to start) need to see something in writing; the testimony of others, at the very least.
From these you can make conclusions and consider things as being possible or probable. Perhaps, as you examine the evidence, you are led TO Him, rather than away from Him. Perhaps the opposite. But again, imo, you can only KNOW the truth... from Him.
(I'm being called away for a bit, so I'll be back to continue further if you would like in a bit)
Peace to you,