I'm a 66-year-old Lutheran. I have a sound religious faith, and have always had a strong interest in learning from reading the Bible. What I've never understood is our concept of God the Trinity: Father, Son and Holy Spirit. I don't know to whom I should pray. I would rather just pray to God. If we're to pray only to God, though, why all this talk about the other two? Also, we're commanded to have only one God.
-- S., Quakertown, Pa.
Nothing scares me more as a rabbi than being asked to explain the Trinity to Christians. However, sometimes an outsider can have a useful perspective. With that disclaimer and my strong suggestion that you consult your pastor, here's what my Christian teachers have taught me about the Trinity: The theological problem the Trinity is meant to address is that the single word "God" is not thick enough, rich enough, nuanced enough or true enough to begin to capture the full mystery of the deity. In the Hebrew Bible, there are three main names for God: Elohim, El Shaddai and the unpronounceable Tetragrammaton, YHWH.
Each name may refer to one or another of God's many attributes. God explains this to Moses directly in Exodus 6:3: "And I appeared unto Abraham, unto Isaac, and unto Jacob, by the name of God Almighty, but by my name JEHOVAH was I not known to them." (King James version) In the case of the Trinity, however, the reason for the three names is not sequential and historical. For Christians, these are three separate but ultimately identical elements of God.
In Hinduism, we see the need to identify different divine attributes in the gods Brahma, Vishnu and Shiva, but this is also different from the Trinity because in Hinduism, these are three separate deities in a huge polytheistic system. Christianity is a monotheistic religion, so the ways the three elements of the Trinity are different are not as important as the way they are the same.
Both Islam and Judaism refer to many attributes of God (mercy, judgment, etc.), but this is also not the same as the Christian notion of the Trinity because they are all attributes of a single God. Mormonism does approach the idea of three deities in complete accord in explaining their belief in the Trinity. Unitarianism believes, like Judaism and Islam, in a single God and is not a Trinitarian Christian denomination.
Jesus taught of the Trinity explicitly in the New Testament: "Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, and teaching them to obey everything I have commanded you. And surely I am with you always, to the very end of the age." -- Matthew 28:18-20 (New International Version)
However, nothing in the New Testament supports the idea of three gods, thus, "The Lord our God is one" (Mark 12:29). To focus on Lutheran beliefs, we begin with the foundation: "Lutherans confess to declare faith in, or adherence to, the faith of the apostolic Christian Church as it is taught in the three Ecumenical (Universal) Creeds: Apostles', Nicene and Athanasian. Namely, that there is only one true God, and yet in this one God there are three persons: the Father, the Son (Jesus Christ) and the Holy Spirit." This means what it says, namely that there is one God, within which there are three persons. It doesn't mean that there are three gods. Each of the persons in the Trinity is completely God, and yet they are distinct. The great problem is in understanding what it means that there are three persons inside of one person. This is the task of the Athanasian Creed (composed probably a century after Athanasius, around the end of the 4th century) that includes this teaching: "We worship one God in Trinity and Trinity in Unity, Neither confounding the Persons nor dividing the Substance. For there is one Person of the Father, another of the Son, and another of the Holy Ghost, but the Godhead of the Father, of the Son, and of the Holy Ghost is all one: the glory equal, the majesty co-eternal. Such as the Father is, such is the Son, and such is the Holy Ghost." The Trinity ought not confuse you into thinking that it is a belief in plural gods. What remains true for all Western faiths is that the mystery of God is far too rich and complex to allow it to be understood the way we understand anything else. The courageous mystery of the Trinity remains a challenging inspiration to all faiths and the single unifying mystery of Christianity.