We know that our old self was crucified with him in order that the body of sin might be brought to nothing, so that we would no longer be enslaved to sin.
Romans 6:6 (NIV)
Christ died to atone for and free you from your sins.
The bondage of sin was broken when Christ crucified your old sinful nature alongside Himself. This means that sin no longer has power over you because you have been transformed into a new creation in Christ. God has given you a new nature and a new desire to please Him and obey His will.
Though sin no longer has control over you, sinful thoughts and habits can still undermine your faith and fill you with fear, guilt, shame, and unbelief unless you walk in your freedom in Christ. Such freedom is possible because you are aware of Christ's victory in your life.
Bear in mind that Jesus defeated Satan on the cross and our rest in His perfect and finished work is the most effective weapon against a conquered foe. Most of the time, we sinned out of restlessness and unconscious frustration. Be aware that the devil will use every opportunity to tempt you to sin because he is the personification of restlessness. He will do everything in his power to erode your faith and impede your progress.
One of Satan’s favourite tactics is to make you focus on yourself and feel sorry for yourself. The more you focus on yourself, the more distracted and restless you become, making you more likely to believe the Enemy's lies. If we do not walk in the reality of Christ’s victory, the devil will continue to ensnare us in sin and keeps us from enjoying that we have in Christ.