How do we explain the concept that God is Three in One? Simply put, God is not three Persons in One Person. The Christian Godhead is THREE separate and distinct Persons with ONE essence.
God the Father, God the Son, and God the Holy Spirit are eternal. They have always been. There hase never been a time when they weren't. While the three Persons of the Godhead have exactly the same essence (characteristics, nature), They have three different job descriptions.
The characteristics of the Godhead (using an acrostic): SELL JR. OOO IV.
S - sovereignty; EL - eternal life; L - love (agape); J - just (fair); R - absolute righteousness;
O - omniscient (all knowing); O - omnipotent (all powerful); O - omnipresent (present everywhere);
I - immutable (unchanging); V - veracity (truth)
The three different job descriptions:
Father: Author of the plan of God (1 Cor. 8:6a)
Son: Executor of the plan of God the Father (Jn. 5:30; 1 Cor. 8:6b)
Holy Spirit: Revealer and restorer to the plan of God the Father (Jn. 14:26; Tit. 3:5; Gen. 1:2)