We like to combine things. That is a part of the modern Western culture. Sometimes we do sowith great results and other times we fail miserably. Unfortunately, when we apply our mentality to the Trinity, we often fail. As we worship a God of three Persons, when we try to come up with an explanation we fall short. Most often we fall into an ancient heresy called Modalism, which tries to break Person of the Trinity into a specific mode of what they do or are. The mystery of the Trinity is not something that, I believe, we will ever fully understand or grasp. God just is.
For this reason, there are those that have broken away from the Trinitarian formula and developed a pseudo-Christian faith that ignores the statements of Jesus like, "I and the Father are One." (John 10:30) In fact, John 10 is full of references which Jesus declares himself to be in the Father while not the Father and the Father to be in him, but he not being the Father. The term Trinity, though not in Scripture, was formulated to clarify this concept more simply to speak about the threeness of God. It also helps us to know and understand the Oneness of God. We do not worship three separate Gods - Father, Son, and Holy Spirit - but one God in three Persons. The Father is God, the Son is God, and the Holy Spirit is God, but they are one God. The greatest explanation was given that attempts to explain this in its fullness is the Athanasian Creed which states:
Whoever wants to be saved should above all cling to the catholic faith. Whoever does not guard it whole and inviolable will doubtless perish eternally. Now this is the catholic faith: We worship one God in trinity, and the Trinity in unity, neither confusing the persons nor dividing the divine being. For the Father is one person, the Son is another, and the Holy Spirit is still another, But the deity of the Father, Son, and Holy Spirit, is one, equal in glory and coeternal in majesty. What the Father is, the Son is, and so is the Holy Spirit. Uncreated is the Father; uncreated is the Son, uncreated is the Spirit. The Father is infinite, the Son is infinite, the Holy Spirit is infinite; Eternal is the Father, eternal is the Son, eternal is the Spirit; And yet there are not three eternal beings, but one who is eternal, As there are not three who are uncreated and unlimited beings, but one who is uncreated and unlimited. Almighty is the Father, almighty is the Son, almighty is the Spirit, And yet there are not three almighty beings but one who is almighty. Thus the Father is God, the Son is God, the Holy Spirit is God And yet there are not three Gods but one God. Thus the Father is Lord, the Son is Lord, the Holy Spirit is Lord, And yet there are not three Lords but one Lord. As Christian truth compels us to acknowledge each distinct person as God and Lord, so catholic religion forbids us to say that there are three gods or three lords. The Father was neither made nor created nor begotten; The Son was neither made nor created, but was alone begotten by the Father. The Spirit was neither made nor created, but is proceeding from the Father and the Son. Thus there is one Father and not three fathers, one Son and not three sons, one Holy Spirit and not three spirits. And in this Trinity, no one is before or after, greater or less than the other, But all three persons are in themselves coeternal and coequal, and so we must worship the Trinity in unity and the one God in three persons. Whoever wants to be saved must think thus about the Trinity. It is necessary for eternal salvation that one also faithfully believe that our Lord Jesus Christ became flesh, For this is the true faith that we believe and confess: that our Lord Jesus Christ, God's Son, is both God and man: He is God, begotten before all worlds from the being of the Father, And he is man, born in the world from the being of his mother, Existing fully as God and fully as man, with rational soul and a human body, Equal to the Father in divinity and subordinate to the Father in humanity. Although he is God and man, he is not divided but is one Christ: He is united because God has taken humanity into himself; he does not transform deity into humanity. He is completely one, in the unity of his person, without confusing his natures. For as the rational soul and body are one person, so the one Christ is God and man. He suffered for our salvation. He descended into hell, and rose again from the dead. He ascended into heaven, and is seated at the right hand of the Father. He will come again to judge the living and the dead. At his coming, all people shall rise bodily to give an account of their own deeds. Those who have done good will enter eternal life, and those who have done evil will enter eternal fire. This is the catholic faith. One cannot be saved without believing this firmly and faithfully.
One must understand the term "catholic" here means universal, as in the universal Christian Church. It was written as a further defense against the Arian influence of the church. What is that? The reason for the Council of Nicea in 325 was because of a fight between two bishops and their followers. Arian denied the deity of the Son, Jesus, while still honoring the Son as a created being of God. They put Jesus, as the Son, next to God but not as God. This controversy still haunts us today within Christianity, particularly with the Mormons, Jehovah's Witnesses, and Unitarians, but elements seem to creep up within what one might consider "mainstream" Christianity. The struggle of the Trinity is nothing new, but it is very important as an aspect of orthodox Christian faith. Each year in the Liturgical calendar we celebrate the mystery of the Trinity on the first Sunday after Pentecost for this reason. It is an opportunity to reflect on the gloriousness of our God that only He can take on the form of the Three-in-One. It is an opportunity for prayer and trust not to explain how it is, but to trust and believe that He is so.