I don’t have a problem with the trinity but I have a friend who does. He asked me why did Jesus say “My Father is Greater than I.” How would you answer that question?
There are a number of verses in the Bible equating Jesus and God. John 1:1, John 10:30, John 14:9, Colossians 1:15, and Hebrews 1:8-9 are examples.
But as for why Jesus said, “My Father is greater than I” (John 14:28), I think Philippians 2:5-11 is the one to use:
“Your attitude should be the same as that of Christ Jesus: Who, being in very nature God, did not consider equality with God something to be grasped, but made himself nothing, taking the very nature of a servant, being made in human likeness.
And being found in appearance as a man, he humbled himself and became obedient to death–even death on a cross!
Therefore God exalted him to the highest place and gave him the name that is above every name, that at the name of Jesus every knee should bow, in heaven and on earth and under the earth, and every tongue confess that Jesus Christ is Lord, to the glory of God the Father.”
The Father is greater than the Son because they agreed to make it so.