I am having trouble with Jesus’ statement in John 14: 28. “You have heard Me say to you, ‘I am going away and coming back to you.’ If you loved Me, you would rejoice because I said, ‘I am going to the Father,’ for My Father is greater than I.” Did He say this because He was still on earth?
Even though the three are one, the Father is always portrayed as the senior member of the Trinity (John 10:27-30). While He was on Earth, Jesus made Himself nothing, taking on the nature of a servant and being obedient unto death.
In return God exalted Him to the highest place, gave Him the name above all names (Phil 2:6-11). He seated Jesus at His own right hand, with a position far above the angelic realm (Ephes 1:20-21), and made Him King of the whole earth as well.
In 1 Cor. 15:25-28 Paul said at the end of His 1,000 year reign, Jesus will again make Himself subject to the Father so that God may be all in all. So He didn’t just say that because He was still on Earth. He said it because it will be true in eternity.