1 Timothy 2:5 says that Jesus is the “one mediator between God and men”.
Since by definition a mediator is someone separate from those who need mediation, it would be a contradiction for Jesus to be one entity with either of the parties he is trying to reconcile. That would be a pretending to be something he is not. So since 1 Timothy 2:5 explicitly states that Jesus is a "mediator" between God and men, this separates Jesus from the entity God and places him between the Deity and us, not equal with God.
As Bar_Anerges so eloquently put it:
"Those who are indoctrinated in the Trinitarian "word magic" will mentally redefine the word "God" in these cases to mean "the Father" or just one of the "persons" instead of the collective Godhead. This is because while the Trinity can separate the Father from Christ it cannot have Christ separated from "GOD." But if Christ were equal to, and the same as Almighty God, he could NEVER be distinguished from *"God"* in any sense." (Entire answer from Bar_Anerges can be found here.)
The Bible is clear and consistent about the relationship of God to Jesus. Jehovah God alone is Almighty. He created the prehuman Jesus directly. (John 1:18; Rev. 3:14; Col. 1:15) Therefore, Jesus had a beginning and could never be coequal with God in power or eternity. (Micah 5:2; 1 Cor. 11:3)
“The Mediator of a New Covenant” (Examination of 1 Timothy 2:5, 6 in the w08 12/15 found at the Watchtower Online Library.)