The doctrine of Scripture is the epistemological foundation of all Christian doctrine, while the doctrine of God is its theological foundation. Only the God revealed in the Bible allows us to understand the Gospel. Theological errors at certain levels generally lead to soteriological or Christological errors. It is therefore fundamental to understand who God is in order to understand everything else.

The Lord our God is the only true and living God. He exists in and of himself, infinite in his being and his perfection. His essence cannot be understood by anyone other than himself.

The doctrine of God affirms His existence as the only uncreated God. Followers of evolutionary theology believe that man's thinking has evolved from polytheism to monotheism and that we can even find this evolution in the Bible. According to this theory, the men of the Old Testament were not monotheists. Of course, they were not polytheists, because they did not worship a multitude of gods, but only the Lord. However, since they recognized the existence of multiple gods, they were henotheists. Henotheism is the recognition of a divinity superior to others. Among the various Mesopotamian and Canaanite gods, the descendants of Abraham made the Lord their own God.

The Bible does not present an evolution of God to monotheism, but affirms this doctrine from the start by presenting the Eternal as Creator of the heavens and the earth. While nothing else existed, God exists from eternity to eternity without ever having begun. The fact that Scripture recognizes other gods does not mean that there are other gods, even if man has created idols. Here is the first passage which is given for this purpose in the confession of faith: 1 Corinthians 8:4 We know that there is no idol in the world, and that there is only one God.  5 For although there are those who are called gods, whether in heaven or on earth, just as there are many gods and many lords, 6 nevertheless for us there is one God, the Father, from whom are all things and for whom we are, and one Lord, Jesus Christ, through whom are all things and through whom we are.

This monotheistic understanding was indeed part of the theology of the people of the Old Testament; Deuteronomy 6:4 Listen, Israel! the LORD our God is the only LORD. There is only one God, which implies that all other gods are false. This is exactly what the Scripture says: Psalms 96:4 For the LORD is great and most to be praised, and to be feared above all gods;  5 For all the gods of the people are idols, and the LORD has made the heavens.

If there is only one God who created everything, how did he begin to exist? He exists in and of himself, infinite in his being and his perfection. God did not start, he is. God is uncreated Ps 90:2 Before the mountains were born, and you created the earth and the world, from everlasting to everlasting you are God. This verse affirms the Creator/creature distinction and prohibits confusing the created and the uncreated, the finite and the infinite.

Men use arbitrary logic when they ask who created God. They arbitrarily refuse that the Uncreated can exist and they demand that everything be explained from their own category of existence where everything has a beginning and an end, a cause and an effect, a finitude and an explanation. God is completely different; he is not simply greater than man and the visible world, he is quidditatively distinct; that is to say, it is of another order, it is radically separated from the category of the created. It is therefore irrational to impose on God criteria of existence valid for man. For God to exist, he must be of himself and of nothing else. Nothing can rise above God to condition or determine his existence and nature and nothing can contain him. Such a God is therefore incomprehensible to the finite reason of the creature.

God said to Moses, I am he who am; Exodus 3:13 Moses said to God, I will go then to the children of Israel, and will say to them, The God of your fathers has sent me to you. But, if they ask me what his name is, what will I tell them? 14 God said to Moses, I am he who am. And he added: This is how you will answer the children of Israel: He who is called “I am” has sent me to you.