As the nature of God is progressively revealed in Scripture, the one God is seen to exist eternally in three persons. These three persons share the same divine nature yet are different in role and relationship. The basic principle at the heart of God's triune being is unity and distinction, both coexisting without either being compromised. Anything that is necessarily true of God is true of Father, Son, and Spirit. They are equal in essence yet distinct in function.
The doctrine of the Trinity is most fully realized in the NT where the divine Father, Son, and Spirit are seen accomplishing redemption. But while the NT gives the clearest picture of the Trinity, there are hints within the OT of what is yet to come. In the beginning of the Bible, the Spirit of God is "hovering over the face of the waters" at creation (Genesis 1:2) and is elsewhere described as a personal being, possessing the attributes of God and yet distinct from Yahweh (Isaiah 63:10). Some interpreters think that the plurality within God is seen in the Hebrew word for God, 'Elohim, which is plural in form (though others disagree that this is significant; the word is used with singular verbs and all agree that it has a singular meaning in the OT). In addition, the use of plural pronouns when God refers to himself hints at a plurality of persons: "Then God said, ‘Let us make man in our image'" (Genesis 1:26-27; cf. Genesis 11:7; Isaiah 6:8). The plurality of God also seems to be indicated when the Angel of the Lord appears in the OT as one who represents Yahweh, while yet at times this angel seems to be no different in attributes or actions from God himself (cf. Genesis 18; Exodus 32:20-22; Numbers 33:38; Judges 6:11-18). There are also passages in the OT that call two persons God or Lord: "Your throne, O God, is forever and ever. The scepter of your kingdom is a scepter of uprightness; you have loved righteousness and hated wickedness. Therefore God, your God, has anointed you with the oil of gladness above your companions" (Psalms 45:6-7). David says, "The Lord says to my Lord: ‘Sit at my right hand, until I make your enemies your footstool'" (Psalms 110:1). The God who is set above his companions (Psalms 45:7) and the Lord of Psalms 110:1 are recognized as Christ in the NT (Hebrews 1:8-13). Christ himself applies to himself (Matthew 22:41-46). Other passages give divine status to a messianic figure distinct from Yahweh (Proverbs 30:4; Daniel 7:13-14).
Taken from the ESV Study Bible copyright ©(2008). Used by permission of Crossway, a publishing ministry of Good News Publishers, Wheaton, Il 60187, www.crossway.org.