Over subsequent visits, he has talked more about his religion, though, and shown that his scepticism of science is really based on countering anything that may undermine his interpretation of the bible. This involves, it transpires, an estimation of the age of the earth at somewhere between 6-10 thousand years. Back to that again. I know - it's just something of a sticking point with me. It seems to me, admittedly a firm atheist, there can be ways of incorporating new information into a faith and that people should not shoot themselves in the foot by flatly denying the obvious. By 'obvious' I'm not saying the earth is definitely 4.55-4.6 billion years old - science works by constantly revising current thinking - but that an age measured in only thousands of years is easily dismissed as nonsense. There are living trees almost 10,000 years old, and so far at least one example much older.
Anyway - he is a very nice guy and clearly very driven. He is, to his great credit, able to at least listen to my responses to his questions and give them some thought. I suspect I will be seeing more of him.