Mark A. Noll in Turning Points on the Nicene Creed:
The bishops who met at Nicaea were not all of one mind, either on the seriousness of the Arian threat or on the best means of meeting it. But their declaration of first principles eventually, after a struggle lasting for most of the rest of the fourth century, became a bedrock for Christian life and theology. The council’s key assertions were as follows:
- Christ was true God from true God. Jesus himself was God in the same sense that the Father was God. Differentiation between Father and Son may refer to the respective tasks each took on or to the relationship in which each stands to the other. But the key matter is that Father, Son, and Holy Spirit are all truly God.
- Christ was consubstantial [of one substance] with the Father. The Greek word used in this phrase (homoousios, from homo-, “same,” and ousia, “substance”) led to great controversy, both because this technical philosophical term is not found in the Bible and because a large faction in the church preferred the assertion that Jesus was “of a similar substance with the Father” (using the key word homoiousios, from homoi, “similar,” plus ousia; later writers referred dramatically to the importance of the distinguishing i, or iota, the smallest Greek letter). In the end homoousios won out because it reinforced as unequivocally as possible the fact that Christ was truly “very God of very God.” The term was held to be a just summary of Jesus’s own teaching, that “I and the Father are one” (John 10: 30).
- Christ was begotten, not made. That is, Jesus was never formed as all other things and persons had been created but was from eternity the Son of God.
- Christ became human for us humans and for our salvation. This phrase succinctly summarized the burden of Athanasius’s concern, that Christ could not have brought salvation to his people if Christ were only a creature. Humanity could not pull itself up to God. Salvation was of God.