Thank you for the question on the fundamental affirmations about God, “What are some of the Bible’s most basic faith affirmations about God?”
Realizing that within the Christian Faith, there is a divergent view on God, but there are fundamentals that most Christians do affirm about God. The affirmations that I list are my own which do not necessarily represent other Christians or Churches. I list Five Essential Doctrines or Beliefs of the Bible:
A. The Bible declares that there is only one eternal, Creator God (Deut. 6:4).
B. The Bible declares that within the Godhead, there is a plurality of being (Gen. 1:1). The plurality of being is God the Father, God the Son, and God the Holy Spirit. There are not three separate Gods, but one God in three person (Matt. 28:18–20).
C. The Bible declares the majestic essence and attributes of God: his sovereignty, holiness, omnipresence, omnipotent, omniscience, faithfulness, and compassion (Exodus 34:6–7).
D. The Bible declares the God has plan for his creation that includes the creation, redemption and judgment of mankind, the return of Jesus Christ, and the restoration of a New Heaven and Earth (John 3:16, Rev. Rev. 20:11–15, 21:1–22:6)
E. The Bible declares that God requires faith in him for salvation and the expression of that faith is seen in good works (Eph. 2:8–10).
SUMMARY: The Gospel of Salvation through Jesus Christ expresses the being and attributes of God.
For more perspectives:
https://www.quora.com/What-are-some-of-the-Bible-s-most-basic-faith-affirmations-about-God