They have His sinless perfection credited to them so that, in Christ, they are forgiven of sin, made legally right with God, and enabled to live in genuine heart obedience to the will of God. Our problem is the problem of sin. The Law informs me that I am a sinner. The Law helps me to see how Jesus is sinless. But we do not think we are nearly as bad as we are.
Sin hardens, blinds, deadens.
Christianity is a sinner's religion. Then, as sinners, we are urged to look to Christ who died to save sinners.