... continued from way back when
B. Three Statements in Summary
Grudem captures the orthodox doctrine of the Trinity (he calls it the biblical teaching on it) in three statements:
1. God is three persons.
2. Each person is fully God.
3. There is one God.
1. God is three persons.
Scripture speaks of Jesus as a distinct person from God the Father. It speaks of the Holy Spirit as a distinct person from Jesus. It uses a masculine pronoun of the Holy Spirit in John, treating him as a person. Since the Spirit intercedes to God the Father, he must be distinct from him as well. The three persons of the Trinity are thus distinct persons from each other.
2. Each is fully God.
God the Father is clearly God. Grudem draws on John 1:1-4 to show that Jesus was fully God. He argues against the Jehovah's Witness' sense that John 1:1 should be translated that the word was a god on the basis of Greek grammar. Colwell's rule states that when a predicate nominative precedes the verb in Greek and the subject follows, the predicate nominative will lack the article (234, n. 12).
Other verses are adduced to support Jesus' full divinity. Thomas calls Jesus God in John 20:28. Hebrews 1:3 says that Christ is the "exact representation" of God's being. Hebrews 1:10, Titus 2:13, 1 Peter 1:1, Romans 9:5, Isaiah 9:6, Colossians 2:9 are all mentioned.
If God the Father and God the Son are God, then surely the Spirit is in the Great Commission of Matthew 28:19. Lying to the Holy Spirit in Acts 5:3-4 is lying to God. Fleeing the Spirit in Psalm 139:7-8 is fleeing the presence of God. So each distinct person is God.
3. There is one God.
Despite there being three distinct persons, each of which is fully God, the Bible seems to require that there only be one God. This faith is the centerpiece of the Shema of Israel in Deuteronomy 6:4 and it is also key to Isaiah 45:5-6, 21-22.
Grudem's next two points in this section are that 4) simplistic solutions all run aground on one of the previous three points and that 5) all analogies have shortcomings. In the next section, he will treat the various errors of those who have tried to oversimplify the Trinity, including those who have erred on the "one God" side and those who have erred on the "all three are fully God" side.
Meanwhile, all analogies fail on one or another of the three basic points: analogies of a three-leafed clover or a tree with three parts or a person who is a farmer, a mayor, and an elder in his church or one person who has intellect, emotions, and will.
Finally, 6) Grudem makes it clear that all three persons have eternally existed as the Trinity.
Grudem's treatment in this section is entirely orthodox. These are the historically shared beliefs of the vast majority of Christendom. He treats in his footnotes a couple outliers--Jehovah's Witnesses and oneness Pentecostals. The former deny that Jesus was God in the same way as God the Father and the latter are "modalists" who believe the three persons were really only manifestations of the same person.
If there were to be a critique, it would be in the interpretations of the proof texts, although there is nothing idiosyncratic about the way Grudem uses them. It is at least possible that many of the passages that have been classically adduced were far more nuanced originally. That is to say, the classic statements of Nicaea (325) and Chalcedon (451) on the Trinity and dual nature of Christ probably reflect more developed understandings of these passages than their original meanings.
For example, it seems more likely that Old Testament passages like Isaiah 9:6 took their original meaning from the fact that kings of the Ancient Near East (ANE) could be conceptualized as God's divine representatives on earth. Such language seems fantastic to us used of a human being but, then again, we have not grown up in the ANE. The New Testament interestingly never uses this passage in relation to Jesus, but it is in keeping with the spirit of the New Testament for later Christians to see the divinity of Christ in it.
Some of the New Testament passages may find their original background in various Jewish traditions that used divine language of the logos (word) or of kings. The Jewish thinker Philo spoke of the logos, the divine word, as the one through whom God made the world (cf. Col. 1:16; Heb. 1:3). We also have evidence of divine language/imagery used of exalted figures like the Son of Man in 1 Enoch, Adam in The Life of Adam and Eve, or even Moses in Ezekiel the Tragedian.
The point is that the original meanings of these verses may have been more nuanced at first than they seem to us today. This explains why there was such long debate over the Trinity and how such differing positions could be taken. The point is not to deny the Trinity in any way but simply to say that God used the flexibility of language to bring Christian thinking on this subject to maturity, just as he did with the New Testament in its understanding of the Old Testament.
So the position that Grudem takes in this section is completely and historically orthodox. This position, however, may require us to put more faith in God's working in the early church than would make Grudem himself comfortable.