“Progressive revelation” is the idea that God revealed more and more of himself as the scriptures were written. Noah, for example, was a righteous man (Gen. 6:8-9). But he couldn’t have quoted the Ten Commandments. They hadn’t been given yet. And Abraham was a righteous man (15:6). But he didn’t know the name of Jesus. The Messiah hadn’t come yet.
The concept of the Trinity is complicated, and God chose to reveal it over time. We find hints of it, though, even in the beginning. The first verse of the Bible introduces God: “In the beginning God created the heavens and the earth” (Gen. 1:1). The second verse mentions “the Spirit of God” (v. 2). This could be understood as two Persons—God and the Spirit of God. And when the Lord announced the intention to create human life, that divine purpose is stated like this: “Let us make man in our image, after our likeness” (v. 26). The personal pronouns in this text are plural. God says “us” and “our” and not “me” and “my.”
The Old Testament scriptures hint at the existence of God’s Son too. In the second psalm David predicts: “The kings of the earth set themselves, and the rulers take counsel together, against the Lord and his anointed” (Ps. 2:2). In Hebrew “anointed one” is Messiah. The Greek translation of “anointed one” is Christ. In this same psalm the Lord says of the coming Messiah, “You are my son, today I have begotten you” (v. 7).
The prophet Micah predicts the birthplace of the Messiah. He writes, “But you, O Bethlehem Ephrathah, who are little to be among the clans of Judah, from you shall come forth for me one who is to be ruler in Israel, whose origin is from of old, from ancient days” (Mic. 5:2). The stunning accuracy of Messianic prophecies is one reason why I believe the Bible is God’s word. There were two Bethlehems in ancient Israel—one in the tribal territory of Zebulun (Josh. 19:15) and the other near Jerusalem in the territory of Judah. Micah is very specific. A “ruler in Israel” will come forth from the Bethlehem (in Judah) formerly known as Ephrath (Gen. 35:16-19).
Micah plainly says that the ruler to be born in Bethlehem would have a pre-life history. His origin was to be from of old, from ancient days. This prophecy is fulfilled in the person of Jesus. The Gospel of John begins: “In the beginning was the Word, and the Word was with God, and the Word was God. […] And the Word became flesh and dwelt among us, full of grace and truth; we have beheld his glory, glory as of the only Son from the Father” (1:1, 14). Jesus, born in Bethlehem (Luke 2:1-7), did indeed have an ancient origin. He was eternal God revealed in human skin.
In the New Testament the Trinity concept is far more fully revealed. The three divine Persons are the Father, the Son, and the Holy Spirit. Each Person is described or named in a variety of ways. The Father is God or the Lord. The Son is Jesus, Christ, the Lord, the Savior, and so on. The Spirit is the Holy Spirit, the Spirit of Christ, the Spirit of God. Several passages refer to all three Persons in the same sentence or paragraph (e.g., Matt. 28:19; 2 Cor. 13:14; Eph. 1:3-14; 1 Pet. 1:2).
But how can three Persons be one Person? They can’t. The Father isn’t the Son. The Son isn’t the Father. The Spirit isn’t the Son. The Bible never implies this impossibility. Three distinct Persons share divine character and characteristics. God is holy, loving, and just. God is eternal, having no beginning or end. God has infinite power and knowledge. He is omnipresent, that is, everywhere at once. All of these things are true of the Father. All of these things are true of the Son. All of these things are true of the Spirit. The Father, the Son, and the Spirit are perfectly united. There is no friction in heaven, no envy or pride, no selfish rivalry (as among the gods imagined by pagans). This complete unity is meant in the biblical claim that God is “one” (Deut. 6:4; 1 Cor. 8:5-6).
The Islamic belief in one divine Person has a serious problem. The Quran praises the Bible. And the Bible says that “God is love” (1 John 4:8, 16). Love is essential to God’s character. He has always loved. He loves now. He will always love. But if God is one Person, whom did God love before the creation? Before God made people, before God made the angels—whom did God love then? Love demands a love object. If God is one Person, his love isn’t eternal. But if God is three Persons, then the Father, the Son, and the Spirit have always had a love object. Jesus speaks of this eternal, pre-creation love in his prayer just before the cross (John 17:24).