Summary: Lessons In Apologetics #9: Theism
The next worldview examined by Geisler in "Christian Apologetics" is Theism. Theism is the belief that a transcendent God created the universe as a reality distinct from Himself but which He actively sustains through both a system of natural law which He created and through divine intervention at the moments He deems such action appropriate for the accomplishment of His divine will. It is Geisler's intention that, since the other worldviews thus far are contradictory and therefore false, Theism is the true worldview.
However, Geisler does not leave readers dangling by requiring them to embrace Theism simply for the lack of another viable alternative. Instead, Geisler provides an argument more positive in its orientation incorporating analytical and evidential components.
The argument is stated as such: "(1) Some things undeniably exist. (2) My nonexistence is possible. (3) Whatever has the possibility not to exist is currently caused to exist by another. (4) There cannot be an infinite regress of current causes of existence. (5) Therefore, a first uncaused cause of my current existence exists. (6) This uncaused cause must be infinite, unchanging, all powerful, all knowing, and all perfect. (7) This infinitely perfect being is called "God". (8) Therefore, God exists. (9) This God who exists is identical to the God described in the Christian Scriptures. (10) Therefore, the God described in the Bible exists."
Borrowing from Descartes' conclusion "cogito ergo sum", Geisler posits that, in order to deny that one exists, one must exist in order to do so. From reflections upon the nature of our own existence, one concludes that our nonexistence is possible. For even though we do not like to admit it, there was a time when the world was at least able to hobble along crippled without us in it.
We know that whatever has the possibility of not existing is currently caused to exist by another. Each of us resulted from the physical union of the genetic material of our respective parents who in turn came from the union of their parents, etc, etc. However, physical laws such as those of thermodynamics point out that this chain must have a cause that does not need to be caused. To accomplish this, the uncaused cause would need to be infinite, unchanging, all-powerful, all-knowing, and all perfect. Anything less would be unable to be this uncaused cause.
It is appropriate to call this cause "God" since it possesses the attributes traditionally assigned to divinity. Therefore, God exists.
Geisler further argues that the God affirmed by this proof is the God described in the Bible because there can only be one infinitely perfect and changeless eternal being. However, at this point in the apologetic task Geisler is careful to point out that, "This does not mean that everything the Bible claims that this God said or did, he actually said or did. Whether or not what the Bible says about this God is another question. What we conclude here is ... the God described in the Bible exists; second, whatever the Bible claims for this God that is not inconsistent with his nature, it is possible that he did indeed do and say (250)."