Peter Leithart notes that Athanasius is famous for his defense of the Christ’s divinity as defined by the Greek term homoousios, which meant that Jesus Christ is of the same substance as God the Father – Christ is truly divine. But Leithart writes that the most important concept in Athanasius’ thought is idios:
Closer to the heart of his understanding of the gospel was a more modest term, the Greek word idios, which describes what is “one’s own,” what is “proper” to a thing or person. “Proper” has to do with something’s most basic “properties.” Human beings are finite; that is proper to their being as humans. God is infinite, good, just, and all these things are “proper” to His being as God.
Leithart explores the implications of this concept in Athanasius’ theology:
- Contrary to the Arian assertion that God existed before the Son did (meaning that there was a time where God was not “Father”), Athanasius could say that we truly pray to a heavenly Father rather than an removed and unknown figure. As Leithart sums it up, “To say that the Son was proper to the Father is to say that the Father was always Father, because He has always, from all eternity, had a Son.”
- Athanasius quoted 1 Corinthians 1:24 which calls Christ “the power of God and the wisdom of God,” saying that Christ had been created by God (as the Arians said), then before this creation God had neither power nor wisdom. Leithart’s summary again: “If the Son is ‘proper’ to the Father, then He is as close to the Father as any of the Father’s attributes. The Father is as much ‘Father-to-the-Son’ as He is good, just, holy, omnipotent, omniscient.”
- In the Incarnation, Christ takes on our flesh as one of his characteristics, as something “proper” to himself. “For Athanasius, it is not accurate to say that the Word Himself, considered as the eternal God, is limited as creatures are. Yet, since He has appropriated flesh, and bound Himself intimately and inseparably to it, He has freely taken on human limits.” These limits include “ignorance” (such asnot knowing the hour of his coming), “weakness” (needing food and drink, experiencing fear), and “suffering and death.”
- Christ has made Christians part of himself as well. “Eternally, the Word is the Power and Wisdom of God. But in history, without ceasing to be that Power and Wisdom, He made Himself our Husband, our Head, our Savior, our Lord. Those titles have become ‘proper’ titles of the Son, because He has made His bride, His body, His people ‘proper’ to Himself. ‘Having-a-bride’ becomes one of the attributes of the eternal Son of the Father.”
Here is Leithart’s powerful summary:
What did Athanasius make of that little word, idios? Most everything: The Father who has a Son that is proper to His essence sent that very Son to take flesh and make the flesh proper to Himself, so that His people could become proper to the Son, and so that we, still living in the flesh, might share by the Spirit in the Power and Wisdom that is proper to the Father.
That, according to Athanasius, is the gospel. That is proper theology.