Others have stated that the Cosmological Argument is sufficient. Some have proposed that the Transcendental Argument for God’s existence (TAG) demonstrates that God exists. (See the article Atheists err when asking for material evidence to prove God’s existence). So, we would have to look for evidence that is consistent with a non-material and transcendent being. If God exists, he would be beyond our universe, non-material, and transcendent. How do you “prove” there is a Great Being outside of our universe? Do we look for footprints in a riverbed? Do we examine evidence under a microscope and say, “A ha! There’s God!”? That would be the wrong approach. But, you see, proof is for mathematics and logic.
Proving that God exists is another matter. So, if you believe Jesus, then God exists. Thus you shall say to the sons of Israel, I am has sent me to you.” In John 8:58 Jesus said, “…before Abraham was, I am.” Whatever you might think of Jesus, according to the Gospels he claimed to be God. Consider Exodus 3:14 of the Old Testament when Moses asked God what his name was, God responded with, “I am that I am. They let us know that he claimed to be God in flesh. These four Gospels are historical documents that tell us who he was and what he did. Atheists deny him, or say they “lack belief in God.” We Christians, of course, not only believe in God but also claim to have a relationship with him through the person of Jesus Christ who has been revealed in the four Gospels of the New Testament. The existence of God has been debated for centuries. Does God exist? Yes, there is a God, but of course, simply saying that God exists does not mean there is one.