I used to think sanctification was a bit like pushing a boulder up a hill. It was hard, slow work, and if you lost concentration you might find yourself back at the bottom. But it’s more like a boulder rolling down a hill. There’s something inevitable about it, because it’s God’s work, and God always succeeds. The sad thing is that often I try to push the boulder back up the hill. I say in effect, “Don’t change me yet – I like doing that sin.”
My lack of faith that the one “who began a good work in [me] will bring it to completion” never fails to amaze me. The beauty and wonder of the Gospel – the very reality that makes it such good news – is that it’s not about me, but about God’s work in me.
And with that mindset, sanctification no longer comes as an undesired struggle and chore, but the wonderful work of God molding and shaping me to be more and more like Christ.
Sanctification is God’s work. But we’re not passive. We have to respond with faith and repentance. And again it turns out that faith and repentance are God’s work in us. So salvation from start to finish is God’s work, in which we are active participants through faith and repentance by the grace of God. We work hard, but then say with Paul, “It was not I, but the grace of God that is with me” (1 Corinthians 15:10). “Work out your own salvation with fear and trembling, for it is God who works in you, both to will and to work for his good pleasure” (Philippians 2:12-13).