At church this morning, we honored both Trinity Sunday and also Father's Day. In seeking to explain how God could be three in one, the pastor essentially presented a modalist model: God is one person, but he reveals himself in three ways, namely, Father, Son, and Holy Spirit. The pastor said that, in the same way that a man can be a father, a grandfather, and a son, and yet be one person, so likewise can God be the Father, the Son, and the Holy Spirit, and still be one person.
I've heard this in a variety of circles. I remember a lady who went to a Pentecostal church---which was not a oneness Pentecostal church, mind you---explaining the Trinity to my Mom and Grandma in a modalist manner. At a liberal Adventist church that I attended, a lady was saying that "person" in the ancient world meant "role"---the mask that a person wore. Consequently, in her telling, the same God performed three different roles: Father, Son, and Holy Spirit.
But I seriously doubt that the Presbyterian church that I attend each week is modalist, for the cover of the bulletin refers to "the Father, the Son, and the Holy Spirit---the holy Trinity, one God in three distinct and equal persons". So the cover of the bulletin presents God as three persons who are distinct and equal, not as one person performing three roles.
The modalism notwithstanding, I liked how the pastor presented the Trinity in his sermon---that God has revealed himself as a Father, as a Son and a servant, and as a Holy Spirit who dwells in people. Because today is Father's Day, the pastor focused on God as Father, and he seemed to use a model of progressive revelation. He stated that the Old Testament depicted God as one who rewarded the good and punished the bad, but the problem with that notion was that we are all sinners. But Jesus revealed God as a Father and a provider---as one who is eager to hear our cares and concerns. Whether or not the pastor's characterization of the Hebrew Bible is completely accurate, I agree with him that the Hebrew Bible can be interpreted as he states, and I appreciate his presentation of God as a loving father---who is eager to listen to us, whether others are or not.
Something that I noticed this morning: We sang "Holy, Holy, Holy", and, in the past, I had problems with that hymn, since it has the line "God in three persons, blessed Trinity". My religious background was Armstrongite, which viewed God as a binity (Father and Son) and as a family that would expand to include believers, not as a Trinity. When I was growing up, my family sometimes attended a Church of God (Seventh-Day) group, which saw God as a binity, though there were many who were unitarian. Instead of the "God in three persons" line in "Holy, Holy, Holy", the Church of God (Seventh-Day) hymnbook had "God ever glorious, praises be to thee." Consequently, I dreaded attending evangelical worship settings in which I'd have to sing "Holy, Holy, Holy". I either did not say the Trinity line, or I said "God in two persons, blessed binity." Either way, my worship was disrupted, since I could not fully enjoy the song.
This morning, however, I sang the Trinity line without any problems. The reason was not that I now believe that the Trinity is the only legitimate way to conceptualize God---which is what I believed about the binity during my Armstrongite days. Rather, I sang it because I honor it as one model for the Godhead, an expression of how people have experienced God. When I was binitarian, I thought that the "early church" was binitarian, and that the Trinity was a pagan incorporation, or merely a human tradition, which lacked biblical support. Nowadays, however, I'm skeptical about our ability to recover the teachings of the "early church".
Some argue that there are different Christologies in the New Testament---as some voices present Jesus as primarily a human figure, whereas others depict Jesus as the incarnation of the eternal God the Word---while others maintain that the New Testament only has one Christology (Jesus as God, or Jesus as a sub-deity). Some contend that the church fathers were all Trinitarian, whereas others have argued that Justin Martyr and Tertullian thought that God the Word had an origin and was not eternal. Some have argued that, even if Jesus was believed to be God by the early Christians, that did not necessarily mean that they held that Jesus was God the way that mainstream Christians today do. Rather, some may have thought that Jesus became God at his birth, baptism, or resurrection, or that "god" can mean a sub-deity---for even Arius (whose view was that God the Word was created) held that Jesus was a god, in some manner. Regarding the Holy Spirit, some argue that the Holy Spirit is a person, since the Bible ascribes to him personal characteristics; others, however, argue that the Holy Spirit is God's power, for the Bible ascribes to the Holy Spirit certain impersonal characteristics (i.e., it can be poured out), and they chalk up the personal descriptions of the Holy Spirit to personification.
I remember reading Whaid Rose of the Church of God (Seventh-Day) saying that the Trinity is a model for the Godhead. I do not know what he means by that, but I, too, view the Trinity as a model. People have experienced God as a Father. The early Christians saw something in Jesus that they regarded as divine---whether it be his love and compassion, or his miracles---and so they came to conceptualize him as God. And people have experienced a personal touch from God---such as God living within them and giving strength to them and communities (such as Christian churches). Many have explained these realities with a Trinitarian model. But others use other models. In my opinion, many Christians (on different sides) are preoccupied with getting the model exactly right, and with dismissing as "heretics" those who do not embrace their model, when they should focus on the reality behind the model: that God is at work in people's lives, and that people have experienced God's love and grace in various ways.