This Creed was formulated at the Council of Nicaea (325 a.d.). It was inspired by the Syro-Palestinian and Eusebius’ creeds. It mentioned for the first time the word homoousios, meaning “the same substance.” This term was condemned during the crisis of Paul of Samosata, but Alexander of Alexandria and Athanasius gave the true meaning. The Creed is thus:
We believe in one God, the Father, the ruler of all, the creator of all things visible and invisible, and in one Lord, Jesus Christ the Son of God, begotten as the only Son out of the Father, that is, out of the substance of the Father, God from God, light from Light, true God from true God, begotten not created, homoousios with the Father, the one through . . .
In the Council of Constantinople (381 a.d.), the following paragraph was added: “We believe in the Holy Spirit . . .” It became a standard declaration of faith for all Christians. The modification of one word—the filioque, in the 11th century—contributed to the final schism between the East and the West. This schism is known as the filioque crisis.