What does it mean to speak of God as "triune?"
Theologically speaking, throughout the Bible, there are repeated references to what is called the "trinity." Dictionary.com defines the "trinity" as:
the union of threepersons (Father, Son, and Holy Ghost) in one Godhead, or the threefold personality of the one Divine Being
Triune also has the same prefix, "tri-" which means three, and is defined, also by Dictionary.com as:
three in one; constituting a trinity in unity, as the Godhead
The three are known as the Father (God), the Son (Jesus), and the Holy Ghost (Holy Spirit). Christians in the Bible are encouraged to pray—and address their prayers—to the "trinity." Prayers are often closed with the phrase, "In the name of the Father, the Son and the Holy Ghost, Amen."
In the Scriptures, God is described as having three separate "manifestations," equal, yet different, each with different responsibilities.
Of the responsibilities each member of the trinity "carries out..."
Each person of the Godhead has an individual mission and the triune God has a collective mission. Jesus was God’s presence on earth and the Spirit is God’s comfort on the earth.
There is also a distinction between the "savior" in the Old Testament, and the Savior of the New Testament:
Jesus assumes the work of Savior in the New Testament. “And she shall bring forth a son, and thou shalt call his name JESUS: for he shall save his people from their sins.” (Matthew 1:21) In the Old Testament, only God was Savior. “I, even I, am the LORD; and beside me there is no savior.” (Isaiah 43:11) Jesus shares equality and authority with God.
Pagewise (©2002), at eSSORTMENT.com, summarizes the triune God, or trinity in the following terms:
God the Father testifies to the Godhood of the Son and sends His Holy Spirit to comfort us. He is also our Judge in heaven, while Jesus Christ is our defense attorney and the Holy Spirit is our intercessor. Each person of the Godhead has a unique function, yet they all share the work of salvation...