Another great argument for the existence of God is the Kalam argument.
There are only three possible options to explain how anything comes into existence. things are caused to exist either: 1) by themselves, 2) by something else, or 3) by nothing.
Option one is clearly absurd: for something would have to pre-exist in order to cause itself; in which case it wouldn’t need a cause — it would already exist.
Option three is also unacceptable, since “nothing comes from nothing.” Nothing, is the absence of anything and thus nothing—being nothing—has no ability to cause anything. Besides, if things could pop into being out of nothing, why doesn’t this happen frequently? Why is it that an elephant doesn’t suddenly appear in the middle of this conversation? I think the most reasonable explanation for things not coming into existence from nothing frequently, is simply because “nothing comes from nothing.”
This leaves us with option two: anything which begins to exist has a cause external to itself.
Now, here is an interesting observation. The best of scientific knowledge currently points to an absolute beginning of the physical universe — specifically, some 13.8 billion years ago when all of space, time, matter and energy essentially “winked” into existence from no prior state of physical affairs.
Furthermore, the second law of thermodynamics also suggests an absolute beginning to space-time reality. If usable energy is running down (as the second law of thermodynamics claims) and yet has not run down completely, this means the universe couldn’t have been “running” forever into the past. To say otherwise means that our universe would already be experiencing the predicted thermodynamic “heat death.” But, our universe isn’t currently experiencing thermodynamic heat death. So, our universe could not have been running infinitely into the past.
But also, the notion of an infinite, backwards series of physical causes seems philosophically—and not just scientifically—untenable. For example: If someone told you they just finished counting down from infinite, you’d be skeptical of this claim, and for good reason. You might believe they finished counting down from some very large number, but you’d rightfully object to the idea they finished counting down from infinite. Because how is that possible?
However, a similar notion applies if we’re to believe the physical universe is eternal into the past—since the fact we’ve arrived at today would imply we’ve somehow finished counting down from infinity. But that can’t be. So, there must have been an absolute, temporal beginning to space-time reality to explain how we’ve arrived at this current point.
So, both scientific evidence and philosophical argument strongly suggest that the universe (space-time reality) had an absolute beginning. But if this is the case—and if it is also the case that whatever begins to exist has a cause external to it—then the universe (all of physical reality) must itself have a cause external to it.
But whatever caused the universe cannot be another physical thing, since whatever brought all of space, time, matter and energy into existence must transcend these created realities. Therefore, we can conclude firmly that there is a timeless, space-less, immaterial, and (obviously) extremely powerful creator of the physical, space-time realm. And this we would call, God.
Furthermore, this creator must be essentially a mind (or mind-like), since the only other possible option for an immaterial reality would be an abstract object, like the number seven. But abstract objects can’t do—or cause—anything; such is the nature of being “abstract.” We are left, then, with just one option: an immaterial, timeless, space-less, eternal and extremely powerful mind which caused physical reality to exist. To most people, that sounds a lot like God.
[Example of The Kalam Argument in a conversation]
So, that’s the Kalam argument, which is a powerful conversational tool, since the argument is not only easy to memorize with its three steps: “everything that begins to exist has a cause; the universe began to exist; therefore, the universe has a cause.” The argument also shows a deep compatibility between modern science and the existence of God.