Wayne Grudem: Chapter Nine: The Existence of God

In chapter nine of Wayne Grudem's Systematic Theology, Grudem addresses the question of how we know that God exists. Scripture, particularly in Romans 1, teaches that "all persons everywhere have a deep, inner sense that God exists, that they are his creatures, and that he is their Creator" (Grudem, 141). Not every person acknowledges this sense because they "suppress the truth" (Romans 1:18) and deny his existence. Sin blinds humanity to their Creator. While the created world, human nature that reflects the image of God, and Scripture testify to God's existence, Satan and sin (2 Cor. 4:4) impair humanity's ability to see the truth about their Creator's existence. Apart from God's gift of redemption, humans are mentally and spiritually handicapped. 

The mental and spiritual impairment that results from sin can only be cured by the grace of God. No argument can succeed where the ability to reason and see are still corrupted by sin. God's effective call must precede the success of any argument that will lead to saving faith. Grace that gives sight is the movement of God to sinful and blind people that must take place if any argument will ever produce a knowledge of God. 

Yet, God's grace does work in and through the carefully considered arguments for his existence. Arguments for God's existence can strengthen the faith of believers by providing further evidence and support for belief in God. Philosophical arguments for God's existence can also remove intellectual objections that unbelievers have to the gospel. 

According to Grudem, there are four traditional categories of argumentation that seek to demonstrate the rationality of the Christian faith. These argument types are:

• Cosmological arguments: These are arguments that relate to cause. It poses the question: how did all that exists come into existence? As Greg Koukl puts it, a Big Bang seems to require a Big Banger. Cosmological arguments lay out why it is rational to think that God was the first cause of all things.
• Teleological arguments: These are arguments that relate to design. How did the complexities of the universe come to be? Teleological arguments argue from evidence of design to the existence of the designer. 
• Ontological arguments: These are arguments that relate to being. Ontological arguments argue that existence is built into the definition of God (a definition that, among other things, could be summarized as the greatest imaginable being).
• Moral arguments: These are arguments that relate to morality. What is morally right and morally wrong? Moral arguments argue that there is a universal moral law and that such a moral law requires a law giver. 

For those interested in further introductions to the philosophical arguments for the existence of God, I would refer you to: 

Geisler, Norman L. Baker Encyclopedia of Christian Apologetics. Grand Rapids: Baker Academic, 1998.  An 864 page volume that provides academic entries on each of these four major arguments.

Strobel, Lee. The Case for a Creator: A Journalist Investigates Scientific Evidence That Points Toward God. Grand Rapids: Zondervan, 2005. In books aimed at a popular audience, Lee Strobel investigates the evidence for faith. In The Case for a Creator Strobel examines the evidence for the belief that the universe had a Creator.

Taylor, James E. Introducing Apologetics: Cultivating Christian Commitment. Grand Rapids: Baker Academic, 2006. This is the textbook used in the Christian Apologetics courses at Tyndale University College and Calvin Theological Seminary. The book is a helpful introduction to some of the arguments for the existence of God and the truth of Christianity. 

Note: I would welcome other recommendations of books that provide introductions to arguments for God's existence. Please share these in the comment section below.