How do we know that Christ has power over Satan?

The New Testament provides numerous accounts of Jesus' authority over Satan and evil spirits, culminating in His victory over sin and death through His atoning sacrifice. In the incident with the Gadarene demoniac in Mark 5, Jesus casts out a legion of demons, illustrating His sovereignty over the spiritual realm (Mark 5:8-13). Furthermore, His death and resurrection are the ultimate manifestations of this power—Colossians 2:15 tells us that through the cross, Christ disarmed the powers and authorities, triumphing over them. This victory reassures believers that while they may face spiritual struggles, they do not have to succumb to the dominion of sin or fear the adversary because Christ has triumphed on their behalf.