Greetings Joseph,
Some others above have mentioned Professor Kreeft’s 20 arguments. I recommend that you get a hold of a copy of his (and Fr. Tacelli’s)
Handbook of Christian Apologetics. I couldn’t say enough about its excellent qualities as an apologetics text, not the least of which are the very good explanations on the various arguments.
Also, some have mentioned William Lane Craig’s Kalam cosmological argument, which is also excellent in that it is very pithy. It consists of 2 premises and a conclusion that necessarily follows from the premises. Most lay Christians find it useful because it is simple enough for anyone to get his mind around.
Also, I didn’t see that anyone above mentioned the Evangelical Thomist, Dr. Norman Geisler. His 2 versions of a contemporary cosmological argument are excellent, especially the one contained in his book
Christian Apologetics. Also see his rev. ed. of
Philosophy of Religion. He may be Evangelical, but he is a Thomist through and through when it comes to the existence and nature of God. I, for one, have never found a more persuasive version of the cosmological argument than the 10 step version that appears in his
Christian Apologetics. The only difficult premise is the 3rd premise on “motion” because Aristotelian/Thomistic philosophy undergirds it, and if you don’t know what Aristotle means by something
metaphysically (not physically) “moving” then you won’t understand the premise. However, Geisler’s explanation on that premise in that book in particular is flat out excellent. Anyone willing to put forth the effort to get through the intricate argument will get a lot out of it. I do find it rationally compelling.
One last thing to note is that the Holy Council Vatican I affirmed that the existence of God
is not merely an article of faith. God can be known to exist with certainty through the natural light of unaided human reason. This is clearly and explicitly put forth as a dogma of faith by the council fathers of Vatican I. Once a Catholic accepts this truth, then the journey begins to find which arguments one finds to be best.
Also, please keep in mind that a Catholic must keep this ever on his mind when trying to be apologetical toward another person. Why? Because usually the other person questioning the faith is
starting from some quirky aspect of reality. That is, of the two most powerful arguments against God’s existence (i.e., the argument from evil & the hiddenness of God argument) both of them neglect to treat the arguments for God’s existence. What I’m trying to get at is that a Catholic would do well to remember that God’s existence can be known with certainty,
apart from any other considerations of reality (e.g., the presence of evil), and then once we have established His existence and learned of His nature, only then do we begin to treat of problems like evil or His so-called hiddenness from His creatures, &c. If you let someone start from, for example, the argument from evil, without having them first (or simultaneously) address the many arguments for God’s existence, it seems like his case is strong. But, this is an illusion because one can fashion the most intricate argument from evil ostensibly demonstrating that God does not exist all day long, but if at the same time that individual completely ignores the multitude of arguments for the existence of God, his argument from evil is ultimately unfounded.
If a person cannot undermine the cosmological argument, then the only rational thing for that person to do is to believe that God exists. Only after this would it be sensible to wonder at the problem of evil.
Hope this helps…
