Athanasius summed up a patristic truism when he said, "God became man so man might become God." All the Church Fathers believed this. 

So, in different ways, did medieval Christians and Zwingli and Bucer and Calvin and Jonathan Edwards and John Wesley. As Carl Moser has argued, deification is a catholic doctrine.

Before the Church Fathers there was Peter, who said God fulfilled His promise so we could become “partakers of the divine nature” (2 Pet 1:4). 

And Paul, who prays that the Ephesians would be filled with all the fullness of God (Eph 3:19). And John, who says when we see Him, “we will be like Him” (1 Jn 3:2).

Athanasius didn’t mean that we become immortal, invisible, omnipotent. No one means that creatures become the Creator. 

We’re created as images of God, and through Christ that image is repaired and comes to its full expression. 

We remain images, but we become as much like the original as a photorealist painting becomes like its subject.

We can be more specific: The Son became man, so man might become son. Adam was created as son of God, and Israel was Yahweh’s son. 

But neither Adam nor Israel grew to full stature as sons. Adam was a child when he sinned, Israel still a minor, under guardians and tutors.

Jesus is the eternal Son of the Father. He took flesh as a man, and so became also a human son of His Father. He’s the first adult.

Jesus didn’t become man so He could become the one and only adult. He became man to bring humanity to mature sonship. 

We’re united to the mature man, Jesus. In and through Him, we become grown-ups, no longer under guardians and managers and the tutor of the law, no longer children.

As sons, we’re adopted into the Triune family. Through the Spirit, we take on a family resemblance to our Father. In Christ, we’re heirs of all things, and, with Jesus, joint rulers of creation. 

This is the gospel: The Son came to bring the world under new management. In Christ, we are the new management, the sons of God the world is waiting for.

This Advent, rejoice: you're sons in the Son. And take responsibility for the corner of the world God has given as your realm. You're an heir. The world is yours to rule.