From my current debate thread:
Ontological vs Economic Trinity:
The Ontological Trinity is the Trinity as it exists in and of itself; that is, how the Father, Son, and Holy Spirit all relate to each other. This is really what the basic definition of the Trinity given above is talking about and to what most people are referring to when they mention the Trinity.
The Economic Trinity is how the Trinity relates to creation. This involves a degree of subordination between the Father, Son and Holy Spirit and would be correctly referred to as economic subordination. This is not to be confused with subordinationism, which is the belief that the Son always has been subordinate to the Father, in nature and being. It is very important to note that economic subordination, or a difference in function, does not indicate an inferiority of nature.
The Ontological and Economical ideas of the Trinity need to be defined upfront as most people read verses showing Jesus as being subordinate to the Father and conclude that he can't be God. However, they are really only arguing against the Ontological Trinity while ignoring the Economic Trinity.
The following is regarding biblical proof of Jesus' pre-existence (all Scripture is from the ESV):
Pre-existence:
Joh 8:57 So the Jews said to him, "You are not yet fifty years old, and have you seen Abraham?"
Joh 8:58 Jesus said to them, "Truly, truly, I say to you, before Abraham was, I am."
Heb 1:2 but in these last days he has spoken to us by his Son, whom he appointed the heir of all things, through whom also he created the world.
Eternal pre-existence:
Joh 1:3 All things were made through him, and without him was not any thing made that was made.
Act 3:15 and you killed the Author of life, whom God raised from the dead. To this we are witnesses.
1Co 8:6 yet for us there is one God, the Father, from whom are all things and for whom we exist, and one Lord, Jesus Christ, through whom are all things and through whom we exist.
Col 1:16 For by him all things were created, in heaven and on earth, visible and invisible, whether thrones or dominions or rulers or authorities--all things were created through him and for him.
Col 1:17 And he is before all things, and in him all things hold together.
this is where the two descriptions of the Trinity--ontological and economical--come into play.
I'll appeal to the NIV for the key passage which shows why Jesus, the God-man, is shown to be submissive to the Father:
Php 2:5 Your attitude should be the same as that of Christ Jesus:
Php 2:6 Who, being in very nature God, did not consider equality with God something to be grasped,
Php 2:7 but made himself nothing, taking the very nature of a servant, being made in human likeness.
Php 2:8 And being found in appearance as a man, he humbled himself and became obedient to death— even death on a cross! (NIV)
Some key points to remember:
1. Jesus was "in very nature God." Pretty self-explanatory.
2. Yet, he "did not consider equality with God something to be grasped," that is, something to be retained or forcibly held on to.
3. He, Jesus, "made himself nothing." (emphasis added) It follows that a) he had the power to make himself nothing, b) if he became nothing, he had been "something," and that something was his "being in very nature God."
4. His being made nothing is further explained as "taking the very nature of a servant," "being made in human likeness" and "being found in appearance as a man." This supports the notion that he had been something, he had been "in very nature God."
5. He "being found in appearance as a man, he humbled himself and became obedient to death." Again, pretty self-explanatory.
Points 1 and 2 provide some of the reasoning behind the ontological Trinity. Points 2 through 5 support the economical Trinity--Jesus' willing submission to the Father for the redemptive purposes of Creation.
Matthew 28:19, 19 Go therefore and make disciples of all nations, baptizing them inthe name of the Father and of the Son and of the Holy Spirit, (ESV)
What is key here is that there is one name (singular, not plural), yet there are three distinct persons as part of that one name. Here is what Vincent's Word Studies says about the matter:
"The name is not the mere designation, a sense which would give to the baptismal formula merely the force of a charm. The name, as in the Lord's Prayer (“Hallowed be thy nameâ€), is the expression of the sum total of the divine Being: not his designation as God or Lord, but the formula in which all his attributes and characteristics are summed up. It is equivalent to his person. The finite mind can deal with him only through his name; but his name is of no avail detached from his nature. When one is baptized into the name of the Trinity, he professes to acknowledge and appropriate God in all that he is and in all that he does for man. He recognizes and depends upon God the Father as his Creator and Preserver; receives Jesus Christ as his only Mediator and Redeemer, and his pattern of life; and confesses the Holy Spirit as his Sanctifier and Comforter."
Jesus accepts worship:
We can find passages in Scripture where at least the Father and the Son are worshiped (all from the ESV):
Joh 20:28 Thomas answered him, "My Lord and my God!"
Mat 2:11 And going into the house they saw the child with Mary his mother, and they fell down and worshiped him. Then, opening their treasures, they offered him gifts, gold and frankincense and myrrh.
Mat 14:33 And those in the boat worshiped him, saying, "Truly you are the Son of God."
Mat 28:9 And behold, Jesus met them and said, "Greetings!" And they came up and took hold of his feet and worshiped him.
Mat 28:16 Now the eleven disciples went to Galilee, to the mountain to which Jesus had directed them.
Mat 28:17 And when they saw him they worshiped him, but some doubted.
Joh 9:38 He said, "Lord, I believe," and he worshiped him.
Yet, even Peter, who was among the eleven in Matt. 28:16 that worshiped Jesus, did not accept worship:
Act 10:25 When Peter entered, Cornelius met him and fell down at his feet and worshiped him.
Act 10:26 But Peter lifted him up, saying, "Stand up; I too am a man."
It is significant that Peter rejected worship on the basis of his being a man.
From the other JW topic:
John 1:1, 1 In the beginning was the Word, and the Word was with God, and the Word was God. 2 He was in the beginning with God. 3 All things were made through him, and without him was not any thing made that was made. (ESV)
The Greek supports the rendering "the Word was God"--even apart from verse 3, but verse 3 does indeed support such a rendering--but that is not all the Greek states.
It is very important to note that John is making a distinction between the Word and God; he is showing us who the Word is, not who God is. I'm assuming that you're appealing to the fact that there is no article before theos. That it appears anarthrously in no way means that it should be translated as "a god," as the following reasons show:
1. If both God and the Word had an article, "the Word was God" would be the same as "God was the Word," but clearly that is not the case.
2. If neither God nor the Word had an article, "God" and "Word" would be interchangeable, equating all of God with all of the Word, but that is clearly not the case either.
3. There are 282 other instances of theos appearing anarthrously and I can all but guarantee that all of them are translated as "God" in the NWT. This includes John 1:6, 12, 13, and 18. So then one is left scratching their head as to why this single instance in John 1:1 is translated as "a god."
There are probably more points I can pull out of the discussions but these are some of the better ones, IMO. In the overall discussion of the Trinity, there is much more that can be said.