SpaceThe Cosmological Argument (also known as the Kalam Argument) goes something like this:

  1. Whatever begins to exist has a cause.
  2. The universe began to exist.
  3. Therefore, the universe has a cause of its existence.

This is a deductive argument, so if we agree that the two premises (1 & 2) are true, then the conclusion (3) is also true. (Which also implies God as the cause for the universe's existence.)

Let's grant that (1) is true; it seems intuitively true that things do not come into existence without a cause. Premise (2) is the major cause for debate. Did the universe begin to exist? Two main arguments support this premise.

First, the philosophical argument. This argument acknowledges that an "actual infinite" cannot exist within the confines of our universe. This refers to both an infinite collection of things and an infinite series of time. While a conceptual infinite may exist (say, within the theoretical world of mathematics, ie "in the mind") a real infinite thing cannot exist in reality. We might observe or conceptualize a potential infinite, that is, something which is approaching infinity, but never actually reaches it. However, actual infinites do not exist in our universe. (Somewhat similar to Zeno's Paradox.) The existence of an actual infinite in our universe would lead to logical absurdities. (See William Lane Craig's "The Existence of God and the Beginning of the Universe" for an indepth examination of this point.)

Objection: "But wait!" some may say, "Christians believe they will live forever with God! Sounds like infinite time to me." While it is true that Christians believe we will spend eternity with God, this still never is an infinite amount of time, since measurement of time between two points will necessarily be finite. Peter Kreeft explains: "Christians believe that their life with God will never end. That means it will never form an actually completed infinite series. In more technical language: an endless future is potentially but never actually infinite. This means that although the future will never cease to expand and increase, still its actual extent will always be finite. But that can only be true if all of created reality had a beginning." (Kreeft, 20 Arguments)

A second reason to accept premise (2) as being true is that scientific evidence points towards the universe having existed a finite amount of time, with a so-called "Big Bang" approximately 15 billion years ago. (For more on this subject, which is too indepth to get into here in a simple blog post, see The Case for a Creator at … essentially a summary of some of the content in Lee Strobel's excellent Case for a Creator book.)

If we accept both premise (1) and premise (2), then we have reasonable reason to believe God exists, as God (as the entity which is behind our universe, being both infinite and great in every way that our universe is not) would be that cause behind the universe. Note that the common objection "Who made God?" either misreads the argument as proposed above (it only necessitates that what begins to exist has a cause, therefore God which has always existed does not need a "cause") or forgets that God (if God exists) requires no cause. This is not special pleading for God; remember that there are both philosophical and scientific reasons why the universe cannot have always existed, whereas neither apply to God.

Go deeper with related readings:

(Thanks goes to NASA's Image of the Day for the space image.)