Logic and God in creation

A couple of quotes from Ken Hams website answers in genesis
www.answersingenesis.com

this is on the back of a lecture last week - can genesis be trusted as text ? if so why - if not why not - this stuff is facinating
---
Those arguing against creation may not even be conscious of their most basic presupposition, one which excludes God a priori, namely naturalism/materialism (everything came from matter, there is no supernatural, no prior creative intelligence).2 The following two real-life examples highlight some problems with that assumption:

1.

A young man approached me at a seminar and stated, ‘Well, I still believe in the big bang, and that we arrived here by chance random processes. I don’t believe in God.’ I answered him, ‘Well, then obviously your brain, and your thought processes, are also the product of randomness. So you don’t know whether it evolved the right way, or even what right would mean in that context. Young man, you don’t know if you’re making correct statements or even whether you’re asking me the right questions.’

The young man looked at me and blurted out, ‘What was that book you recommended?’ He finally realized that his belief undercut its own foundations —such ‘reasoning’ destroys the very basis for reason.

2.

On another occasion, a man came to me after a seminar and said, ‘Actually, I’m an atheist. Because I don’t believe in God, I don’t believe in absolutes, so I recognize that I can’t even be sure of reality.’ I responded, ‘Then how do you know you’re really here making this statement?’ ‘Good point,’ he replied. ‘What point?’ I asked. The man looked at me, smiled, and said, ‘Maybe I should go home.’ I stated, ‘Maybe it won’t be there.’ ‘Good point,’ the man said. ‘What point?’ I replied.

This man certainly got the message. If there is no God, ultimately, philosophically, how can one talk about reality? How can one even rationally believe that there is such a thing as truth, let alone decide what it is?