We have been fitted with the full armor of God, the belt of truth, the breastplate of righteousness, the shield of faith, the helmet of salvation, in our hand is the sword of the Spirit, which is the word of God and our feet is fitted with the readiness that comes from the gospel of peace. (Ephesians 6:13-17)

Christians are not called to defeat Satan. God has already done that in Christ! Nor is it our mandate to “bind” Satan. Jesus has already set limits on the extent and duration of Satan’s freedom. Satan, “our ancient foe,” was decisively and completely defeated by Christ’s sacrifice on the cross and in His resurrection. With regard to Satan, our assignment is to trust in the victory that Christ already achieved and daily resist him with the truth of his defeat, as Jesus did.

Satan is the father of lies and a master deceiver (John 8:44). If he can convince you that God has not defeated him, then you will not experience Jesus’ victory. You will find yourself fighting battles that Christ has already won! You will fear Satan though he has already been utterly and humiliatingly defeated. Your responsibility is to resist Satan, and he will flee from you (James 4:7). When you resist him, you are acknowledging that Jesus has defeated him and given you victory over his influence. God has provided you with spiritual armor that is more than sufficient to withstand any assault by Satan (Ephesians 6:10-20).

Christians can become preoccupied with battling Satan. This deceives them to invest their time and energy attempting to do something that Christ has already done for them. If Satan can divert you to wage a warfare that has already ended in surrender, he will have eliminated your effectiveness where God wants you. Fearing Satan is fearing a prisoner of war. You have no need or calling to defeat Satan; you need only to apply Christ’s victory in every area of your life and to live the victorious Christian life.

Source: Experiencing God Day by Day