Biblical Christianity teaches that God is not created, but discovered by us. Better said, He reveals Himself to us through various means. His primary means of self-disclosure is the Word of God, the Bible.
However, what about before the Bible? The Bible is not an eternal book in the sense that it had no beginning. There came specific points in human history when God the Holy Spirit led Moses to write the first five books of the Old Testament, the Apostle Paul to write over half of the New Testament, and someone (who knows who?) to write the epistle to the Hebrews! These were men guided by the Spirit of God (2 Pe. 1:21) who used their literary talents to write what God wanted written.
But what about before then? The Bible is quite clear that God has always been revealing truth about Himself. Through nature, human nature, and history He has communicated truth about Himself. Listen to Romans 1: 18 The wrath of God is being revealed from heaven against all the godlessness and wickedness of people, who suppress the truth by their wickedness, 19 since what may be known about God is plain to them, because God has made it plain to them. 20 For since the creation of the world God’s invisible qualities—his eternal power and divine nature—have been clearly seen, being understood from what has been made, so that people are without excuse. 21 For although they knew God, they neither glorified him as God nor gave thanks to him, but their thinking became futile and their foolish hearts were darkened. 22 Although they claimed to be wise, they became fools 23 and exchanged the glory of the immortal God for images made to look like a mortal human being and birds and animals and reptiles.
Theologians refer to this revelation as natural revelation. That is, God has through the creation communicated truth about Himself to all people everywhere. Note what Romans 1 says:
1. God’s wrath has been revealed because man suppresses the truth that nature gives about God (v.18).
2. There is a plainness to God’s communication in nature: His eternal/invisible qualities have been clearly seen (vv. 19-20).
4. In their rejection of “natural” revelation, man’s own thinking has been adversely affected! His thinking has become futile, leading to a darkening of the human heart (v. 21).
5. Man has made a terrible exchange. He has swapped God’s glory for idols! John Calvin put it this way: “man’s nature is a perpetual factory of idols.”
But natural revelation is still true — and is still there for us to point to. We can proclaim with Psalm 19 “The heavens declare the glory of God; the skies proclaim the work of his hands.”