The trinity has its roots in ancient Babylons false religion. Jesus had a prehuman existence with his Father in Heaven and prayed to him while he was with us on earth. Why would a God pray to himself?
It's also said that the trinity has roots in the ancient Egyptian trinity. Or that Christ is based on the god Mithra or Horus or Zeus, etc....
For the same reason that Jesus said he didn't know the hour of his return....only the Father knows that. So, does this contradict Jesus' deity? Not even a little bit. Why did the Son of God come to Earth in the form of man and live among his creation as any man would? He came to fulfill what Israel could not in the OT while at the same time establishing a new covenant with man. Christ came and submitted to the Father so that we may recognize how we should submit to God's will. He fellowshipped with men, he ate with men, he traveled with men, he taught men, he lived as a man. But make no mistake, Jesus Christ is God. Christ forgave sins, Christ raised the dead, Christ healed the sick, Christ commanded demons, Christ miracously fed multitudes. Christ affirmed his deity and gave undeniable examples of his deity, but didn't return to his glory until after he was crucified and rose. Before his resurrection he chose to live as man, but fully connected to his divine Fatherly essence in heaven. Based on that connection, he did the impossible and affirmed that he was God while still existing in a limited form as a man - a limited existance he choose. As a man he maintained his connection with his divine essence through prayer, but his act of prayer was also an example for man to follow. He lived as a man so that we may understand how to live and submit to God. Why did he also choose this limited state as a man? Simple, because God can't die (he is eternal), but a God who limits his form to that of a normal man can die. He came as the perfect man, the perfect sacrifice that died for all forgiving all sins for those that claim him as their risen Lord and Savior. After his resurrection his returned to his full glory and power as the divine Son of God that always existed at the right hand of the Father. As the resurrected Son of God he was transformed and those closest to him didn't recognize him at first because he transformed into his divine state. He then displayed the divine ability to instantly move from place to place as only God can and reclaimed his omniscient status as the Son of God who knows all things.
John 11:41-42
41 So they rolled the stone aside. Then Jesus looked up to heaven and said, “Father, thank you for hearing me. 42 You always hear me, but I said it out loud for the sake of all these people standing here, so that they will believe you sent me.”