“The thief on the cross did not have time to ‘become a better man.’ He could not ever have a new life or any good deeds to boast of. And yet no man has ever received a more unconditional promise of salvation. He had done the one thing that is necessary – he had come to Jesus to get his help. He believed in Jesus.
“In the presence of Christ we must never expect to find a gathering of morally perfect people. ‘Now the tax collectors and sinners were all drawing near to him.’ ‘Many tax collectors and sinners were sitting with Jesus and his disciples; for there were many who followed him.’ Whoever finds himself in this category must do the same. He who does not do this should not be surprised to find a mixed company in the church of God.”
– +Bo Giertz+
We do not become “better” by our effort. This is Pharasaism/legalism. Instead, we become better when Christ makes us new, imputing to us His righteousness.