Although I agree that the teaching on the Trinity is inaccurate, the Trinity is not a myth though
In order for people of that time and even now, to be able to comprehend who and what God is, He described Jesus as his son, but Jesus is actually God himself in a physical form.
Jesus was that portion or part of God that came to earth as the form of a man
God is God,Jesus and Holy Spirit, but the concept is very difficult for us to comprehend, so God explained it in a way that we could understand bettter and accept.
He described that part of himself that came to earth as the son, and because that part of himself was in a physical form, it had temporarily divested himself of his glory and power, so while in physical form that part of God was in a sense not equal with the other two parts of God.
The idea of a being being 3 in one and yet able to seperate a part of themselves and change that part into a different form while still being a part of the whole, is very difficult for us to understand, but the way it is explained as father and son is a lot easier for us.
However jesus is not God's son, Jesus is God in the form of flesh.
Still, there needs to be further prayer and meditation to hear from the Holy Spirit as a great deal of the teachings in churches come from the distorted ideas and idiology of the Catholic church, which is not a true church, but an instrument of the devil.

