There are many varying arguments for the existence of God. These arguments are either a priori, understood independent of worldly experience and observation (Ontological Argument), or a posteriori, dependent on experience and based on observations of how the world is (Cosmological and Teleological Arguments).
For my first basis for the existence of God I will use the a posteriori, ontological arguments. Ontological arguments are a priori, which show that God exists without appealing to a sense experience. These ontological arguments argue about what God is to where he is .
from. St. Anselm, the creator of the ontological argument, based his theory on that we cannot think of anything greater than God. Therefor God must exist, why you might ask? If the greatest thing that we can conceive does not exist than we can still conceive the greatest thing that does exist, and that would be God. Descartes views God in a similar way to St. Anselm. Descartes sees God as the perfect being while St. Anselm describes God as "that than which nothing greater can be thought." In Descartes "the Argument from Perfection" he reasons that if existence is one of the perfections and God has all the perfections, then God must exist. Along with these arguments others in the Jewish, Christian, and Islamic communities have similar views. .
Cosmological arguments are a posteriori, these tend to lean toward proving the existence of God through a sense experience. Cosmological arguments come in many varieties, such as the existence of the universe to God as its creator, cause, or explanation. Cosmological arguments were started at the time the questions of the universe were first asked. The existence of motion to the existence of a first mover as the cause of movement, was argued by Aristotle. This first mover he called God. The reason for this was that nothing caused God to move yet God was responsible for the motion of all other things.