I think Aquinas's arguments, while valid, simply go over the head of most modern atheists, who lack the philosophical background to understand them. As God is, by nature, immaterial and outside of the material universe, rather than some physical "thing" in it, doctrinaire materialists will simply deny His existence, as God cannot be directly observed or measured by science but this is simply close-minded materialistic dogmatism, rather than proof of His non-existence.
I actually just got a book, New Proofs for Existence of God: Contributions of Contemporary Physics and Philosophy, by Robert J. Spitzer, SJ
, and am currently working my way through it. It's serious intellectual stuff, and not an easy read, at least for a non-astrophysicist like me, but so far it's pretty compelling, though some of the sections regarding physics went over my head. Rather than rehash Aquinas, it offers (as the title indicates) arguments from modern physics and philosophy, which may be more compelling to modern thinkers.
I haven't gotten to the philosophical section yet, but the first part concerns modern astrophysics and theories regarding the origin of our universe. In the first section, Fr. Spitzer basically argues that the current evidence overwhelmingly indicates that the universe (time/space) has a definitive origin, rather than coming out of material that has existed eternally prior to the "big bang." He discusses various "bouncing universe" and "multiverse theories," and points out the considerable problems each of these theories raise. He then discusses the so-called "anthropic principle" and the extreme mathematical unlikelihood that a universe would have the properties necessary to make the development of life possible, and the physical problems with multiverse and superstring theories, which themselves would involve considerable "fine-tuning" of properties in order to work. In short, he shows how it is much more reasonable to conclude that the universe came about from an immaterial, intelligent cause (ie. God), rather than from random material occurrences.
It's heady, involved stuff, and won't make for pithy soundbites in an internet "debate," but I'd recommend it for anyone seriously interested in these issues, particularly those of a serious physics or science geek persuasion. L_D would likely enjoy this book.
Edited by Socrates, 14 June 2012 - 04:22 PM.