The Creator Was Known as the True God from the First by His Creation. Acknowledged by the Soul and Conscience of Man Before He Was Revealed by Moses
For indeed, as the Creator of all things, He was from the beginning discovered equally with them, they having been themselves manifested that He might become known as God. For although Moses, some long while afterwards, seems to have been the first to introduce the knowledge of the God of the universe in the temple of his writings, yet the birthday of that knowledge must not on that account be reckoned from the Pentateuch. For the volume of Moses does not at all initiate the knowledge of the Creator, but from the first gives out that it is to be traced from Paradise and Adam, not from Egypt and Moses.
The greater part, therefore, of the human race, although they knew not even the name of Moses, much less his writings, yet knew the God of Moses; and even when idolatry overshadowed the world with its extreme prevalence, men still spoke of Him separately by His own name as God, and the God of gods, and said, “If God grant,” and, “As God pleases,” and, “I commend you to God.” Reflect, then, whether they knew Him, of whom they testify that He can do all things. To none of the writings of Moses do they owe this.
The soul was before prophecy. From the beginning the knowledge of God is the dowry of the soul, one and the same among the Egyptians, and the Syrians, and the tribes of Pontus. For their souls call the God of the Jews their God. Do not, O barbarian heretic, put Abraham before the world. Even if the Creator had been the God of one family, He was yet not later than your god; even in Pontus was He known before him. Take then your standard from Him who came first: from the Certain (must be judged) the uncertain; from the Known the unknown.
Never shall God be hidden, never shall God be wanting. Always shall He be understood, always be heard, nay even seen, in whatsoever way He shall wish. God has for His witnesses this whole being of ours, and this universe wherein we dwell. He is thus, because not unknown, proved to be both God and the only One, although another still tries hard to make out his claim.
Source: Against Marcion (New Advent)