I don't know where--haven't read the dusty thing in awhile..if that tells you anything, but I believe it's mentioned 'somewhere' in the 1st 4 Books of the NT, i.e., Matthew, Mark, Luke and John [i.e., essentially the same boring story rehashed 4x over; with whatever so-called observation(s)/artifacts that were ómmitted' by the 1st author of the epistle, were picked up by the remaining 3 authors sort of leaves me with a rather sour impression of inconsistency, or gaps in time where writer 'witnessed' JC do this and that, while the others 'witenessed' JC do that and the other. {That's when I decided the last book of the NT should have just ended with the book of Revelation after the book of John. It's full of errors due to mistinterpretations by scholars who laborously transliterated the whole thing from the original Greek text.
I think we're supposed to be impressed by the additional sources. It just wasn't implemented very well. Maybe they have discrepencies in order to seem more real? Either way it's just as likely they were all written by one person with a lousy memory.
I think the thread topic violates all sorts of rules against fallacies. It's a loaded question to say the least. Maybe, here's a revised version of the question: IF Jesus existed, IF he walked on water, then how did he walk on water?
Now it's more hypothetical, but at least we non-believers can have access to it. So how would one go about in faking such a magic trick back 2000 years ago. The answer? Fairly easily. If you look at the surface of a lake or a river, etc. at any given time it can differ in luminescence depending upon the amount of light available and viewing angle. It can range from completely transparent to sompletely dark under different circumstances.
If we assume he walked on dark water he could have used preset poles, which would allow him dip something in the water to prove its depth. Of course there are probably to many methods to list here: stilts, anchored rafts below the surface, inflatable shoes, a tightrope or 2 strung along the plane of the body of water, etc. So I repeat, it's pretty easy. Just as easy as faking one's own death, switching water for wine and any number of other cheap parlor tricks.