Jesus' teaching refers to the Father as the "Only True God," indicating that the Father is the highest among all gods. This does not deny the existence of other divine beings but asserts the Father's supreme authority over them. John 17:3 records Jesus saying, "Now this is eternal life: that they know you, the only true God, and Jesus Christ, whom you have sent.”
When the Father sends a messenger, a prophet, they can minister to others what the Father, God, has given them. The Son of this God is Jesus, the Lord, the Christ. He too fulfils the will of the Father and may cooperate with the Father to teach and empower the one being sent. If they believe, and they accept correction and chastisement from the Father, they are treated as His children and the Father may give them the Holy Spirit, as promised. They might be sent by this Holy Spirit too, to do the will of the Father in the way of Jesus. So now they can go with threefold authority. They have authority in the name of the Father. They have authority in the name of the Son. They have authority by the authority of being sent by the Holy Spirit. With many of those sent, it might be the Son and Holy Spirit each sending them. Yet the authority of the Father is included because the Son and Holy Spirit have this authority and can relay it to those they send. Some might only experience the Holy Spirit at the very start of their ministry such as when hands of elders are laid on them and a church send them. Yet the authority is still relayed to them of Father and Son too, by extension. If they have been sent to make disciples and baptise them, then it will be by all of this authority. They might only be sent to teach about those who have sent them, relaying the knowledge given them by Father and by Son and by Holy Spirit. They would do so in all of this authority. This is how the church first came to be built up. It is still built this way today.
