Today we reached Arius in the course on the Trinity. It is quite fascinating to see the various attempts made by fathers, ecclesiastical writers and heretics, to address the problem of how there can be only one God and yet there can also be Jesus Christ and the Holy Spirit. Tertullian came up with the term "Trinitas" and there were various more or less successful attempts to say how the Son or the Word could be distinct from the Father and yet be God.
Some thought that the Son was an emanation from the Father, perhaps a secondary God, or that he was God and therefore the same as the Father, so that the Father also suffered on the Cross. Others said that he was like a ray from the light source, that he was God in a sense but not the true God. Arius said that he was created, not eternally begotten, and that he was of a different kind of thing from the Father, not of the same substance.
In the next session, we will take a look at the response of the Fathers of Nicea and the Creed which we say or sing at Mass. Knowing something of the struggle to express the faith in words, it is thrilling to affirm in the words of those Fathers in 325:
And [we believe] in one Lord, Jesus Christ,
the only Son of God,
eternally begotten of the Father,
God from God,
Light from Light,
true God from true God,
begotten, not made,
consubstantial with the Father.