An attempt to prove God's existence first postulated by Anselm. In brief, it states that God is a being of which no greater thing exists or can be thought of. Therefore, since we can conceive of God as the greatest of all things that exist, then God must exist.
An attempt to prove that God exists by appealing to the principle that all things have causes. There cannot be an infinite regress of causes, therefore, there must be an uncaused cause: God.
The world everywhere reveals intelligence, order, harmony, and purpose, and thus implies the existence of an intelligent and purposeful being, adequate to the production of such a world.
Kant: categorical imperative - from it inferred the existence of someone who, as lawgiver and judge, has the absolute right to command man. Others: disparity often observed between the moral conduct of men and the prosperity which they enjoy in the present life, and feel that this calls for an prosperity which they enjoy in the present life, and feel that this calls for an adjustment in the future which, in turn, requires a righteous arbiter.
Historical or Ethnological Argument
Among all the peoples and tribes of the earth there is a sense of the divine, which reveals itself in an external cultus [worship]. Since the phenomenon is universal, it must belong to the very nature of man. And if the nature of man naturally leads to religious worship, this can only find its explanation in a higher Being who has constituted man a religious being. In answer to this argument, however, it may be siad that this universal phenomenon may have originated in an error or misunderstanding of one of the early progenitors of the human race, and that the religious cultus referred to appears strongest among primitive races, and disappears in the measure in which they become civilized.