The first Sunday after Pentecost is Trinity Sunday, and it is devoted to the consideration of the Triune God. From the first Sunday in Advent until this Sunday, the Moravian Church reflects upon the revelation of God as made known in the earthly life of Christ Jesus. The revelation of the facts of salvation culminates in the outpouring of the Holy Spirit as celebrated on Pentecost. Then the Church adds one more festival, Trinity Sunday, to reveal the constitution of the Godhead, which made the divine plan of salvation possible.
God the Father evolved the plan. In other words, he created the blue print of Salvation for the redemption of the world. God the Father is the first person in the Godhead.
While God the Father created the blue print for Salvation, God the Son carried it out. He did so by His life, death and resurrection. He cared enough to give His life as a sacrifice and a ransom for the redemption of the world. The carrying out of the plan meant that the wounded are healed; the blind receive sight; the deaf hear and the dumb speak; the crippled walk; those who are in mental, physical and satanic slavery are emancipated and set free.
God the Holy Spirit applies the blue print or plan to those who are being saved. The Holy Spirit is the comforter to be with us forever. The Holy Spirit, the third person in the Godhead, completes the Trinity.
Trinity" is a term that is not found in the Bible, but a word used to describe what is apparent about God in the Scriptures. The Bible clearly speaks of God the Father, God the Son (Jesus Christ), and God the Holy Spirit and also clearly presents that there is only one God. Thus the term: "Tri" meaning three, and "Unity" meaning one, Tri+Unity = Trinity. It is a way of acknowledging what the Bible reveals to us about God, that God is yet three "Persons" who have the same essence of deity.
Some have tried to give human illustrations for the Trinity, such as H2O being water, ice and steam (all different forms, but all are H2O). Another illustration is an egg having a shell, egg yolk and egg white, but this egg illustration shows that there would be "parts" to God, which isn't the case.
God the Son (Jesus) is fully, completely God. God the Father is fully, completely God. And God the Holy Spirit is fully, completely God. Yet there is only one God. In our world, with our limited human experience, it's tough to understand the Trinity. But from the beginning we see God this way in Scripture. Notice the plural pronouns "us" and "our" in Genesis 1:26 -- Then God said, "Let us make man in our image, in our likeness, and let them rule over the fish of the sea and the birds of the air, over the livestock, over all the earth, and over all the creatures that move along the ground."
The Trinity is a very important Doctrine in the plan of salvation and one which the Moravian Church holds dearly.