It's by grace

The identity of Jesus within Scripture is never finally interpreted because it is textually mediated. Second, because it is textually mediated, Christ is not contained within Scripture, but is made known to us through it. Although Scripture’s depiction of Christ is part of the economy of salvation, Christ is not the text itself. And third, because the righteousness we receive as the image of God is renewed in us is simply the restoration by grace of God’s creative intent, we do not overwhelm Christ’s identity because we never cease to be creatures. The righteousness Christ gives us is his human righteousness. That is, we do not receive the divine nature itself by participating in the means of grace. We become only by grace what he is by nature.— Reading the Way to Heaven, pages 141–42