Arguments for the existence of God

• the ontological argument, based on arguments about the "being greater than which nothing can be conceived"
• the cosmological argument, which argues that God must have been around at the start of things in order to be the "first cause"
• the teleological argument, which argues that since the universe is highly non-random, it must have been designed by an intelligent designer, God
• argument from common consent: people in all times and places have believed in God, so who are you to disagree
• argument from morality: since morality cannot exist without God, God must exist
• transcendental argument for the existence of God: logic, science, ethics, and other good things don't make sense if God doesn't exist. Therefore God does.
• Christological argument is specific to Christianity - become a Christian and believe in God

There have also been some arguments against the existence of God. The primary one is the problem of evil.

See also: philosophy of religion, metaphysics