We believe in one God,
the Father almighty,
maker of heaven and earth,
of all things visible and invisible.

And in one Lord Jesus Christ,
the only Son of God,
begotten from the Father before all ages,
God from God,
Light from Light,
true God from true God,
begotten, not made;
of the same essence as the Father.
Through him all things were made.
For us and for our salvation
he came down from heaven;
he became incarnate by the Holy Spirit and the virgin Mary,
and was made human.
He was crucified for us under Pontius Pilate;
he suffered and was buried.
The third day he rose again, according to the Scriptures.
He ascended to heaven
and is seated at the right hand of the Father.
He will come again with glory
to judge the living and the dead.
His kingdom will never end.

And we believe in the Holy Spirit,
the Lord, the giver of life.
He proceeds from the Father and the Son,
and with the Father and the Son is worshiped and glorified.
He spoke through the prophets.
We believe in one holy catholic and apostolic church.
We affirm one baptism for the forgiveness of sins.
We look forward to the resurrection of the dead,
and to life in the world to come. Amen.

The highlighted phrase was reaffirmed at the council of Constantinople in 381 AD. The Nicene creed insisted that Christ was “of the same substance as the Father”. The dispute with Arius concerned two words, homoousios (of the same nature) and homoiousios (of a similar nature). The difference depends on the different meaning of the two Greek prefixes, homo meaning ‘same’ and homoi meaning ‘similar’. Arius was happy to say that Christ was a supernatural being and that he was created by God before creation. The Council of Nicaea and Constantinople realized that this did not go far enough, for if Christ is not of the exactly the same nature as the Father, then he is not fully God. So, both councils insisted that orthodox Christians confess Jesus to be homoousios, of the same nature as God the Father.

It should be emphasized that every rebuttal to the views of Arius and other heretics is firmly grounded in Scripture. These are not merely the opinions of the Church, but the authoritative witness of Scripture standing against heresy.