A “true believer” doesn’t have their faith built around that cloth (unless you mean they’re a true believer in the cloth... in which case, of course).
The better question is, what happens if *man* “proves” it’s real? False prophets, false idols, like I said at the beginning, and very dangerous for the people in this thread who’ve proven they fall into this category.
Hebrews 11:1 - Now faith is the substance of things hoped for, the evidence of things not seen.
1 Corinthians 2:5 - That your faith should not stand in the wisdom of men, but in the power of God.
John 20:29 - Jesus saith unto him, Thomas, because thou hast seen me, thou hast believed: blessed are they that have not seen, and yet have believed.
You have no idea how much I envy someone capable of feeling faith.
I have never seen anyone on any Shroud thread whose faith is based on anything about the Shroud being real of not. That is a construct of the skeptics who perpetually invade the threads to throw brickbats at believers in Christ, especially Catholics, not the Shroud, or at those who clothe themselves in the pride of the superiority of their own faith’s purity, a sin in and of itself. For those, I think their Holier-than-thou attitude is being noted where it counts in the “Judge Not, lest ye be judged” category.