The (sometimes intimidating) book of Revelation, which caps off the New Testament, holds one of the most powerful verses in the Bible, in my opinion. When speaking of the accuser (Satan), Revelation 12:11 (NIV) tells us,
"They overcame him by the blood of the Lamb and by the word of their testimony; they did not love their lives so much as to shrink from death."
Did you catch that? "By the word of their testimony," Satan is overcome. Jesus' shed blood and resurrection from the dead are enough to overcome Satan all on their own, but we rub salt in his wounds by our testimonies. By sharing.
Satan is defeated by Jesus' sacrifice, and by our telling others how He's changed our lives.
Hold on. I don't think you're entirely convinced yet. Let me tell you a story.
Mark 5 tells the story of the demon-possessed man. Ever heard the phrase, "We are Legion" before? This story is where that comes from.
This man had a herd of demons within him, and this is causing him to do many harmful things. He's kept in the tombs outside of the city, and we're told that he couldn't even be bound with chains, because he would merely break them off.
He would run around madly, cutting himself and crying out loudly. Mark 5:6-7 tells us,
"When he saw Jesus from a distance, he ran and fell on his knees in front of him. He shouted at the top of his voice, 'What do you want with me, Jesus, Son of the Most High God? Swear to God that you won't torture me!'"
Couple things about this.
1) A man possessed by demons sees Jesus and runs to Him. He doesn't shy away or try to hide; he runs. He knows that he can't escape Him. Which brings me to my second point.
2) The demons within this man admit Jesus' status as the Son of God. James highlights this idea by saying, "You believe that there is one God. Good! Even the demons believe that--and shudder" (James 2:19). Demons know who they answer to, and they know who to be afraid of.
Jesus casts the demons out of this man, and the man is made right in his own mind once again. The people in the town, who knew this man, were shocked by this change. Afraid, they begged Jesus to leave their town, for they knew not what kind of man He was.
The (formerly) demon-possessed man begged Jesus to let him go with Him. But Jesus tells him, "Go home to your family and tell them how much the Lord has done for you, and how he has had mercy on you" (Mark 5:19).
Jesus doesn't give him an out by letting his escape his town. He doesn't let him walk away from people who have seen him at his worst.
Rather, Jesus knew that the change incurred in this man would reap the best benefits by becoming apparent to all those who knew his worst side.
Think about it. Say you're a drug addict, and you get clean. If you move to a place where no one knows who you are or what you've been like, you saying, "I used to be a drug addict but now I'm clean" won't have that great of an effect.
But if you stay where people have seen you at your lowest, and you show them that your change is legitimate, the power of your testimony will be great.
It's only by the power of Jesus that this man can go back into his town and proclaim the triumph over the demons. So too, it's only by the power of Jesus that I can tell you how He's made a difference in my life.
It's by sharing those experiences, big or little, that we weaken Satan. Every little triumph of Jesus' just chips away at whatever semblance of strength Satan thinks he has.
Speak up. Go and tell others how much the Lord has done for you. Tell others how He has had compassion on you. Do it.
Do it knowing that through every word you speak in Jesus' name, Satan gets smaller, and smaller, and smaller.