Illuminatalie and Brain in a jar:
I had one of that happen to a guy where I worked. I didn't know him except by sight until the proccess was well along. From things he said, it could not have taken more than two years.
This guy had a MS degree in mechanical engineering so it was amusing to watch his fundie "knowledge" collide with his engineer knowledge.
He liked to play tapes from creationist radio shows at work, so I asked him about that. He parroted the usual line about uranium dating doesn't work because how can we know how much uranium was in the rock originally. I explained that garnet had uranium in it's chemical formula so we know to the last atom how much uranium it had, just like we know exactly how much oxygen is in H2O. He just skipped merrily on to we don't know how much lead the rock had in it originally.
I then told him everything in those tapes is a lie. They lied to you about the uranium, and they're lying to you about lead and everything else. He couldn't deny what I said about the uranium, apparently he took enough chemistry in engineering school to realise that, but because I refrained from telling him that garnet has no lead in it's chemical formula, therefore any lead in it must have been added later, he continued to claim there was no way to know how much lead it had originally. The fact that the tape lied about that regarding uranium didn't affect his opinion of it's reliability. He just accepted it was wrong about uranium and accepted everything else it said.
Later I told him about garnet and lead, and if the missing uranium=the lead that shouldn't be there but is then we can rule out lead and uranium moving in and out of the rock therefore the uranium date is valid for this rock. He was forced, by his knowledge gained in engineer school that uranium dateing is valid, but he still believed everything else the tape said was true. The fact that I didn't debunk everything it said in detail meant to him that these were irrefutable proofs that the bible was true.
This person was an unusual fundy in that, unlike the vacuum heads that usually get submitted here, he understood technology and physics and math and basic common sense, and could not claim the bible is true because 2+2 might=5 instead of 4. I wanted to do a lot of experiments on him, but there was a wave of layoffs about then and I didn't get the chance.
He seemed to know in some sense that his fundie beliefs made no sense. When I asked questions where the correct fundie answer contradicted the correct engineer answer he looked like he was in pain when he answered me with the correct fundie answer. When I then explored the situation with him, forcing him to answer basic common sense (by mechanical engineer standards) questions that added up to his religion being wrong, he gave up trying to win the argument on that issue, but he still had total confidence that his religion was right and what science said was wrong and continued to repeat what the tapes told him.