I think when most people think about Christian growth or what it means to progress in the Christian life—they would never say it this way—but the implication is we needed Jesus a lot for justification and we need him less for sanctification.
Christian growth, the way many people think about it, is we are becoming stronger and stronger, we’re becoming more and more competent, and yet the Bible makes it pretty clear, certainly Paul does, when he says he’s accomplished more than any of us could ever do for Jesus, and yet at the end of his life he says, “I’m the worst guy I know” (I Cor. 15.9). This signals to me that Christian growth and progress in the Christian life is not, I’m becoming stronger and stronger, it’s I’m becoming more aware of just how weak I am.
It’s not that I’m becoming more and more competent, it’s that I’m growing in my realization of how incompetent, how dependent I am on Christ. He stood condemned in my place and sealed my pardon with his blood. Hallelujah! What a Savior! The Christian life is not about my transformation; it’s about Christ’s substitution. He did for me what I could never do for myself, and that’s why Paul was so free at the end of his life to say, “I’m the worst guy I know! And it’s okay for me to tell you that because, in Christ, I have no reputation to protect. I don’t need to pretend. I don’t need to put on masks and make you think that I’m something I’m not. I am free—absolutely free—to say from the rooftops I am the worst guy I know, Jesus paid it all.”
I already possess everything in him. It’s about him; he’s the hero of the story, I’m not. This entire thing has nothing to do with me and it has everything to do with him. And when we rest in that, our hearts are gripped by it and our lives are totally changed and transformed because we’re no longer thinking about our transformation—we’re thinking about Christ’s substitution. – Tullian Tchividjian (in an interview entitled This Entire Thing Has Nothing to Do with Pastor Tullian)