How do we know that Jesus has authority over demons?

In the narrative of the Gadarene demoniac, we witness Jesus exercising His divine authority over a legion of demons. The demons, recognizing Jesus as the Son of the Most High God, plead for mercy rather than confronting Him, demonstrating that His power supersedes their own. Jesus' simple command, "Come out of the man, you unclean spirit," leads to an immediate and complete deliverance (Mark 5:8). This incident reinforces the Reformed understanding that all creation, including spiritual beings, is ultimately subject to Christ's sovereign will. As believers, we find assurance that Jesus, having triumphed over evil, secures our victory in spiritual battles through faith in Him.