Are you confusing Jesus' role as a Mediator with his role as High Priest?
They are one and the same.
My question though, was how that differs from being created, in terms of not having existence, and then existing at some point in time. This may be an impossible question to answer.
As I mentioned before, the bible talks on several occasions about Jesus being Creator, not being created. Sure, Jesus became flesh, and was born but He existed before that. Try this chapter Hebrews 1
If Jesus is begotten of God, wouldn't that mean that at some point in the past, he was unexisting?
Not necessarily. We know Jesus already existed before He was begottern of God, see the ve
And yes, Jesus atoned for the entire sin of the world. Yet, (again from a WT view), what was lost was a perfect Man in Adam. Thus, Jesus, being equally a perfect man, could provide an exact replacement for Adam. No?
In a legal sense, wouldn't each party of the covenant (God & Humanity) need to be represented equally by an impartial party, who ensures both sides fulfil the terms of the covenant? Like a mediator? How could the covenant be mediated if one party was the same as the mediator?
These verses explain who Jesus was and what He became to come and mediate for us.
Philippians 2:5-8 (English Standard Version)
5 Have this mind among yourselves, which is yours in Christ Jesus, 6 who, though he was in the form of God, did not count equality with God a thing to be grasped, 7 but made himself nothing, taking the form of a servant, being born in the likeness of men. 8 And being found in human form, he humbled himself by becoming obedient to the point of death, even death on a cross.
Coming from a WT perspective, how would a perfect Man not be able to fulfil the requirements of a sinless life, to atone for Adam's life? Why does it need to be a God-man?
Because all who are in Adam sin.
Mark 10:17-18 (New International Version)
17 As Jesus started on his way, a man ran up to him and fell on his knees before him. “Good teacher,” he asked, “what must I do to inherit eternal life?”
18 “Why do you call me good?” Jesus answered. “No one is good—except God alone.
1 Corinthians 15:22 (New International Version)
22 For as in Adam all die, so in Christ all will be made alive.
Romans 3:22-24 (New International Version)
22 This righteousness is given through faith in Jesus Christ to all who believe. There is no difference between Jew and Gentile, 23 for all have sinned and fall short of the glory of God, 24 and all are justified freely by his grace through the redemption that came by Christ Jesus.
Blessings in Christ,