How do we know Christ's victory over Satan is assured?

The assurance of Christ's victory over Satan is central to the message of Revelation. In Revelation 12:11, we see that believers overcome the devil by the blood of the Lamb. This signifies that Christ's sacrificial death and subsequent resurrection provides the definitive victory over the powers of darkness. Believers can rest in the fact that their sins are forgiven and they are justified before God because of His finished work on the cross, allowing them to resist and ultimately overcome evil.