The Gloria Patri – “Glory be to the Father and to the Son and to the Holy Ghost; as it was in the beginning, is now, and ever shall be, world without end. Amen.” Is added to the end of the Psalm as a confession of the Blessed Trinity.
Bowing at the waste when the Name of the Holy Trinity is sung is an old practice of the Christian Church. Bowing shows honor to the Name of our God, Who has revealed Himself as the Blessed Trinity: Father, Son, and Holy Spirit.
After chanting the Introit, the Kyrie comes next. Kyrie is a Greek word meaning “O, Lord”. Traditionally, Kyrie is sung three times. Pleading the Lord for mercy. In Divine Service Settings 1 & 2, the Kyrie is stated as a fivefold prayer.
When the Kyrie is sung three times, it is based on the order of events in Luke 18:35-43. There a blind man calls out for mercy from the Lord. Just like we do. He cried persistently. We cry three times. His prayer was answered. And so are our prayers. Then he and “all the people with him” glorified and gave praise to God. Our Kyrie is followed by us glorifying and praising God with the Gloria in Excelsis.