The great Welsh preacher Martyn Lloyd-Jones said, ​“Our greatest need is to become who we already are in Christ.”

True! Beautiful! But how do we do that?

A metaphor may help, one of the great metaphors of the Kingdom of God: the seed.

The oak is in the acorn. You might say that the acorn is becoming what it already is.

This picture of a seed may help illuminate the difference between new life and mature life. At the moment we decide to follow Jesus we are given the seed of new life. It is something real that didn’t exist in us before. While the miracle of growth is the work of God, cooperating with God in that growth is up to us. This is why E. Stanley Jones says, ​“Conversion is a gift and an achievement” — because while we can’t earn the seed of new life given to us, we can put effort toward its care.

There’s a related picture for Christian spiritual formation in Galatians 4:19, one of the key verses for Renovaré: ​“My little children, for whom I am again in the pain of childbirth until Christ is formed in you.”

What does it mean that Christ wasn’t fully formed in them? Clearly, Jesus isn’t incomplete or lacking in any way. The unformed substance in them was the life of Jesus. The Christ-life in them was still immature, still embryonic — alive and real but needing to mature. How did Paul know that their Christ-life was tiny and immature? Because they were back to earning their place with God, back to relying on ​“religious plans and projects,” as The Message puts it.

If that’s what an unformed Christian looks like — a person doing a bunch of seemingly good stuff to try to gain favor with God — what does the formed Christian look like?

Alive. Free. Grace-empowered. Rather than keeping a scrupulous eye on their own (or anyone else’s) spiritual temperature or perfect behavior, the mature person keeps their eyes on Jesus and acts for others’ best. ​“The only thing that counts,” Paul says, ​“is faith expressing itself through love.”

As for how this maturing happens, a classic article from Richard Foster offers a helpful overview of the means God uses to shape us to be like Jesus. Helping people enter into that life is why Renovaré exists.