christianity

Discussions in other forums spawned by my previous post seem to have boiled down to an essential question.

How do we establish the trustworthiness of Christianity's claims about Scripture in a way that multiple, contradictory claims by other faiths are not all rated as equally trustworthy?

So far, the person who started the conversation with me keeps appealing to presuppositional dodges: "If we first accept that Scripture is true..." isn't a very reassuring start to a discussion of why Scripture is trustworthy. I wouldn't normally press this particular point, but the original question was his and I'm hoping that I can salvage something out of it.

Anyone out there who has something to offer, please chime in. It's not an attempt at a sucker-punch; I'm just trying to suss out how reasonable this expectation even is.