ONE GOD IN THREE PERSONS
The Father, Son, and Holy Spirit are not three gods but one God in three Persons. Each Person is fully God, sharing the same divine essence. They are eternally distinct yet completely united—three "whos" in one "what."
One. Israel's most basic confession: there is one God, and only one.
Echad is the ordinary Hebrew word for "one." It can count a single thing ("one day," Genesis 1:5) or describe things made one ("one flesh," Genesis 2:24).
The Shema: "The Lord our God, the Lord is one."
A man and his wife become "one flesh."
Asked which commandment is most important, Jesus starts with the Shema.
"One God, the Father… and one Lord, Jesus Christ." Paul seems to echo the Shema, with Jesus included in its one Lord.
The Shema, named for its first word, "Hear," is Israel's central confession. By the first century, Jews were praying it every morning and evening, and faithful Jews still do. In a world full of gods, it said there is one.
The first Christians were Jews who kept praying the Shema while worshiping Jesus. Paul even seems to echo its words to include Jesus within the one Lord (1 Corinthians 8:6).
Centuries later, a church leader named Arius taught that the Son was a created being. In AD 325 the Council of Nicaea chose the word homoousios, "same being," to say clearly that the Son shares the one being of God.
A church leader in Alexandria, Egypt, who taught that the Son was created. His teaching is what the Council of Nicaea answered.
A young deacon who went to Nicaea with his bishop and later became bishop of Alexandria himself. He defended the Son's full divinity for decades and was sent into exile five times for it.