In my discussion with David, I wanted to come up with some kind of explanation that might show how I see the naturalist worldview. I realize there are far more brilliant men who can do a far better job than I am able, but here I go.
From my perspective, what I am hearing from David is that in a naturalistic universe, creatures evolve. One of these creatures becomes some kind of advanced caveman who discovers thoughts in a manner other creatures don't. He discovers laws of logic or that at least logic is needed to think coherent thoughts. He discovers that he is reasoning and using reason to think coherent thoughts. He realizes he is using words to articulate sentences. He doesn't care why these things are. They are just a part of this creation just as he is in some sense.
Then one day, he sees his fellow caveman, whom he called Cain, take a knife and kill another caveman, named Abel, in order to get his female. He realizes this is wrong and proceeds to tell Cain of his "evil".
Cain in turn explains to Caveman #1 that he is full of nonsense. Why just this morning he watched a starving lion eat her young. He recalled that their pet tiger had murdered an antelope last week. So he explained to the first caveman that there is no such thing as evil or murder and that the thoughts in his head were just chemical reactions (really smart caveman). Cain explained that he had just used conventional thoughts to force him to do something he did not want to do and to restrain him from doing something he wanted to do. In fact, he thought that was wrong if anything was going to be wrong.
Now Caveman #1 realized the inherent problem. If Cain is right about morality, then by logical extension, the other discoveries he had made were also problematic. So he instead tries to make a purely naturalistic case of why their lives would be better if....
Now of course one may take this and go in several directions with it. The point is presuppositions matter. I would further argue that people don't really think or live this way (even if it is in some kind of Schizophrenic way, living in a naturalistic world and a created world). Men intuitively know when something has a creator. No one would look at David's art and think David painted it beautifully because of some chemicals in his head accidentally did it that way. For the term beautiful must have a higher transcendent meaning to even use the word in this fashion. This is part of the Apostle's evidence that demonstrates that men suppress the truth and existence of God and instead exchange the Creator for that which is created.
In my view, to even have a discussion such as this in a purely naturalistic world is just a complete waste of time. Eat, drink and be merry. For tomorrow we are going to die. It is no wonder that so many intuitively live this way as well. Without Christ's resurrection, if God doesn't exist, so what, and if God does exist, we are doomed.