The following excerpt comes from Tim Chester’s You Can Change (p. 25, 27):
What’s wrong with wanting to change so we can prove ourselves to God or people or ourselves? It doesn’t work. We might fool other people for a while. We might even fool ourselves. But we can never change enough to impress God. And here’s the reason: trying to impress God, others, or ourselves puts us at the center of our change project. It makes change all about my looking good. It is done for my glory. And that’s pretty much the definition of sin. Sin is living for my glory instead of God’s. Sin is living life my way, for me, instead of living life God’s way, for God. Often that means rejecting God as Lord and wanting to be our own lord, but it can also involve rejecting God as Savior and wanting to be our own savior. Pharisees do good works and repent of bad works. But gospel repentance includes repenting of good works done for wrong reasons. We need to repent of trying to be our own savior. Theologian John Gerstner says, “The thing that really separates us from God is not so much our sin, but our damnable good works.”
Deep down in all of us there is a tendency to want to prove ourselves, to base our worth on what we do.
Here’s the real problem with changing to impress: God has given his Son for us so that we can be justified. Jesus died on the cross, separated from his Father, bearing the full weight of God’s wrath so that we can be accepted by God. When we try to prove ourselves by our good works, we’re saying, in effect, that the cross wasn’t enough.
(HT: It’s a Beautiful Gospel)