We have a most difficult doctrine before us here. A mystery and a matter of FAITH as we cannot explain or rationally make sense of. The fathers introduced the apostolic confession with the trinity as He is mentioned in it as the truth comes to the fore in confessing the Word of God! Three persons in ONE God are revealed to us in His Word and their fellowship is extended to us!
It truly is incomprehensible. A mystery and we cannot fathom or comprehend it in or with our finite minds. We are dealing with God. The God who says "unto whom will ye liken me?!" He is incomprehensible and we approach this material with fear as any image of God is idolatry. God is ONE and THREE in persons. We are one in person and one in being and we cannot explain or understand having 3 persons within one being that can all individually say "I" in perfect harmony. Truly a matter of faith!
Although scripture is not a dogmatic book He reveals Himself historically in His Word as it progresses from Genesis to the new testament. He speaks of "letting US make man in our image." We find the Trinity in the Psalms with God putting His Son Christ at His right hand. We move to the new testament and the doctrine of the Trinity is revealed and comes to light at Pentecost as we see the voice from heaven. The Holy Spirit descending from heaven in the form of a dove. The Spirit of truth coming from the Father and the Son. I John 5 states that THREE bear witness! The vastness of scripture testify to the Trinity. The same God that speaks and fellowships with Himself!
These things do have personal experience in the child of God and we experience them in our lives. God the Father and our Creator who makes application to us so we know we are in His hands. And God the Son who was like us in all things sin excepted to come in the flesh to die and save us from our sin in our redemption being our Redeemer! And we can trace this from the very beginning until He is at God's right hand in glory. And the Holy Spirit is also revealed. Ananias and Sapphira lied to and they dropped dead. The one who sanctifies and leads us so we are holy. God the Father, Son, and Holy Spirit. Not theology, but One we experience in our daily lives.......
God the Creator. God the Redeemer. God the Sanctifier. He who believes in the Trinity must think thus!