The following two arguments are currently my favorite apologetic arguments for the truth of theism, and by way of subsequent inference to the best explanation, Christianity. I have written about them many times, and enjoy both discussion and answering questions about them. I am going to discuss them both briefly and leave it for your consideration.
The first argument is the kalam cosmological argument (KCA). Cosmological arguments for God’s existence reason from the contingent facts of the universe to a transcendent cause of the universe. The kalam is a particular formulation of this idea. Thus, there is no one singular cosmological argument, only a family of arguments that share the basic foundation in common. There are two versions of the KCA that have been presented by its most prominent defender, William Lane Craig. I will give what I call Craig’s classical presentation, then his current presentation, and then discuss them both. Here is the classical presentation of the KCA:
1. Whatever begins to exist had a cause.
2. The universe began to exist.
3. Therefore, the universe had a cause.
And here is the current presentation:
1*. If the universe began to exist, then the universe had a transcendent cause.
2. The universe began to exist.
3*. Therefore, the universe had a transcendent cause.
The first thing to notice is that (2) appears in both arguments. This is a great premise because it enjoys both philosophical and scientific support. On the philosophical side, of the several arguments given, I like the argument against traversing an actually infinite amount of time. It doesn’t appear possible. Think about it this way: if you pick an infinitely distant “starting point” (any arbitrary point will do) in the past, an infinite number of moments would have to pass for you to arrive at the present moment. But before the present moment could arrive, the moment prior would have to arrive; and before that moment, the one prior to it would have to arrive, and so on and so forth ad infinitum. But then the present moment could not arrive, since the infinite series could never be traversed! It’s like encountering a man who claims he has just finished counting all the negative numbers from infinity down to zero; it doesn’t make any sense!
Further, there are scientific reasons to think the universe began to exist. In pop culture, even today, it is not uncommon to hear things like, “The universe is eternal and infinite.” But this is just scientifically outdated (by about a hundred years!). Scientists have discovered the universe is expanding. Extrapolating the rate of expansion backward into the past, they have postulated there is a point in the past where all matter is condensed into a single miniscule point. They further postulate that this point “burst” to spread out and form the universe over a long period of time. They call this the Big Bang Theory, and it implies a beginning to space. Regardless of what one thinks of this theory, you cannot have both the old model of endless, eternal space and the Big Bang. You must have one or the other, or neither. The point is just that current scientific models suggest one cannot avoid an absolute beginning to the universe.
(1) is good, in that it is both intuitive and constantly confirmed by our experience. Some people have thought that a counterexample to (1) would be quantum events. However, this is confused. (1) does not say, “whatever event transpires has a cause,” but whatever begins to exist had a cause. The difference means that in order for quantum events to be a counterexample, the virtual particles would have to come from nothing. But they do not come from nothing; they come from a sea of energy.
However, Craig reformulated (1) into (1*) perhaps in part to avoid this whole confusion in the first place. (1*) seems eminently plausible; the alternative is to think that the universe both came into existence and had no cause whatsoever, which seems very, very counterintuitive, to say the least! But then it follows that the universe had a transcendent cause. This transcendent cause, then, must be timeless, spaceless, immaterial, extremely powerful, personal, beginningless, changeless, and uncaused! That sure sounds a lot like God—specifically, the God of the Abrahamic tradition.
Now here is the version of the moral argument that I prefer:
1. If God does not exist, then objective moral values and duties do not exist.
2. Evil exists.
3. Therefore, objective moral values and duties do exist.
4. Therefore, God exists.
I prefer the extra step (3) provides for reasons I shall explain in a moment. (1), I think, should be placed in probabilistic terms: probably, God is the best explanation for objective morality. Think about it this way: in the absence of God, why should we be good? To whom do we owe that obligation? It cannot be merely other humans, for humans did not always exist, and there could be other sentient moral agents that exist or could possibly have existed, and presumably morality could apply to them. So, without such a ground, it looks like moral obligations wouldn’t be around at all.
Now, as it turns out, all you need at this point is for someone to agree that objective moral values and duties do exist. However, some people resist this point initially. It is here I like to remind the objector of what his favorite (likely) argument against God is: the problem of evil. The problem of evil works only in cases where, in fact, there is evil. Beheading people for the faith, calculated genocide as ethnic cleansing, imprisonment for thought crimes—these people take to be evil deeds, not just deeds we happen not to like. You can provide myriad examples, and usually people grant that at least some things are objectively evil. If they do not, however, do not lose heart: you have shown a cost—a very, very great cost—of accepting their view: you must stand firm in the counterintuition that nothing is really wrong, deep down: it’s all preference.
In any case, once one accept (2), it entails (3), and (1) and (3) entail (4), that God exists. Now this God is plausibly a necessary being, since it looks like moral truths are necessary, and God grounds these.
So take these two arguments alone and combine their conclusions: there exists a being who is plausibly necessary, transcends the universe, brought it into existence, grounds objective morality, is omnibenevolent, beginningless, changeless, uncaused, timeless, spaceless, immaterial, enormously powerful, and personal. For a variety of reasons, I think this is best represented by the Christian God. What do you think?