Tim Chester in You Can Change:
The key to change is continually returning to the cross. A changing life is a cross-centered life. At the cross we see our source of sanctification (Ephesians 5:25–27; Colossians 1:22; Titus 2:14). We find hope, for we see the power of sin broken and the old nature put to death. We see ourselves united to Christ and bought by his blood. We see the glorious grace of God in Jesus Christ, dying for his enemies, the righteous for the unrighteous. We see our hope, our life, our resources, our joy.
At the cross we find the grace, power, and delight in God we need to overcome sin. If we don’t come to the cross again and again, we’ll feel distant from God, disconnected from his power, and indifferent to his glory — and that is a recipe for sin.