As analogies go, I think this is the best: Have you ever heard of severely conjoined twins? Identical twins who did not completely separate in an early stage of their development in their mother’s womb and end up sharing so much of a single human body that they look more like a two-headed human than two separate humans? The Trinity is analogous to severely conjoined divine triplets. Three distinct but inseparable divine persons who share a single divine nature. Each divine person, because he shares the one divine nature, can rightly be called God but, because they are as inseparable as severely conjoined twins, the three divine persons form a single divine being, one God, not three separate Gods.
It is wrong to think that the Father existed before the Son or the Son before the Spirit. Rather, the three divine persons have always existed as one divine being, as distinct and inseparable from one another as severely conjoined twins. There was never a time when the Father was not begetting the Son and never a time when the Spirit was not proceeding from the Father and the Son.
If that was not complicated enough, some 2000 years ago, the uncreated Son, who has existed with the Father and the Spirit for all eternity, distinct but inseparable from them, was united to a newly-created human nature in the womb of the Blessed Virgin Mary. Since that (hypo-static) union of the divine person (the Son) with a human nature, we happily refer to the Son as Jesus Christ.
Try not to be confused by expressions, such as Son of God and Spirit of Christ. They are not meant to deny the divinity of the Son nor of the Spirit. They are simply used to differentiate between the three persons of the Trinity. With respect to divinity, the words God, Father, Son, Spirit, and Jesus Christ are all synonymous. The first person of the Trinity, eternal and uncreated, is called the Father, God, God the Father, the God and Father of our Lord Jesus Christ, etc. The second person of the Trinity, eternal and uncreated, is called the Son, God, God the Son, the Son of God, our Lord Jesus Christ, etc. The third person of the Trinity, eternal and uncreated, is called the Spirit or Holy Spirit, the Spirit of God, the Spirit of Jesus Christ, etc. It might seem strange that Jesus Christ would refer to his Father as God if Jesus himself was God but consider that a doctor can refer to his doctor as doctor without denying that he too is a doctor.
In those places in Sacred Scripture where Jesus suggests that he is in some way inferior to the Father, I would offer that by those expressions he intends to show his voluntary submission to the Father, though he himself is otherwise the Father’s equal, sharing the same divine nature.
