God Is
Some philosophers, such as Wittgenstein, take a view that in some ways is considered anti-realist and oppose philosophical arguments related to God's existence. For instance, Charles Taylor contends that the real is whatever will not go away. If we cannot reduce talk about God to anything else, or replace it, or prove it false, then perhaps God is as real as anything else.
Of Witness
Christianity and Judaism assert that God intervened in key specific moments in history, especially at the Exodus and the giving of the Ten Commandments in front of all the tribes of Israel, positing an argument from empirical evidence stemming from sheer number of witnesses, thus demonstrating his existence.
Christological
The argument from the Resurrection of Jesus. This asserts that there is sufficient historical evidence for Jesus's resurrection to support his claim to be the son of God and indicates, a fortiori, God's existence. This is one of several arguments known as the Christological argument.
Christian apologetics
Christian apologetics has taken many forms over the centuries, starting with Paul the Apostle, including writers such as Origen and Augustine of Hippo, and continuing currently with the modern Christian community through the efforts of many authors in various Christian traditions such as G.K.Chesterton and C. S. Lewis. Apologists have based their defense of Christianity on historical evidence, philosophical arguments, scientific investigation, and arguments from other disciplines.
God Is Not
1. If the law is against you pound the facts
2. If the facts are against you pound the law
3. It both the law and the facts are against you pound the table
4. If you don't have an argument… abuse the other side.