[person nr. 1]: "The Bible is true because God says so in the Bible."
[person nr. 2]: "-But at SOME point you have to have SOME piece of evidence, otherwise you're only believing the word of someone who lived thousands of years ago?"
[person nr. 1]: "Of course. The Bible contains prophecies that had a 100% success rate."
[person nr. 2]: "OK - that's good news. Are they verifiable through other sources than the Bible?"
[person nr. 1]: "Yes - we have archeology that shows that some of the kings and other persons of the Bible lived pretty much around the time that the Bible says."
[person nr. 2]: "OK, but can you prove that the biblical books were written before the events in the prophecies took place, and not after?"
[person nr. 1]: "Yes, if we follow the chronology in the Bible, we see that they..."
[person nr. 2]: "...Hang on - aren't you about to use the Bible in order to prove the Bible right??"
[person nr. 1]: "Well - as I said, archeology does show us that the Bible is historically correct on several occasions."
[person nr. 2]: "Yes, but are there any outside sources that confirm that those prophecies were written before the events took place? Are there tablets or scrolls found dating to before the events took place?"
[person nr. 1]: "Erhm... No."
[person nr. 2]: "Well, then how can I be sure these things weren't written down after the fact?"
[person nr. 1]: "You have to have faith in the word of God at some point."
[person nr. 2]: "OK, but why should I?"
[person nr. 1]: "Because the Bible says so, and the Bible is the word of God."
(OK - a little cheesy and not exhaustive in its explanation, but you get the point)