What if Christianity isn't true and I've built my life around it?

Then you should want to know.

The amount of time, identity or emotion you have invested in Christianity cannot make it true. But neither does the fear of having "wasted" years make it false.

That is why sunk-cost reasoning works both ways. Staying only because leaving would be painful is a bad reason to believe; abandoning Christianity simply because discovering you were mistaken would feel embarrassing is not a good reason either.

Christianity makes claims about reality, including a striking historical claim: Jesus was raised from the dead. Paul himself says that if Christ was not raised, Christian faith is empty.

That gives you permission to investigate rather than protect Christianity from questions.

You may not reach mathematical certainty. Historical questions rarely offer that. But you can ask the more useful question: which explanation best fits the evidence we actually have?