Revelation 12:11 (NIV) 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.  

Believing Wins the Battle!  Apostle  John  has  just  described  (Rev. 12:1-6)  the  age-long,  cosmic  battle  between  Satan,  God,  and  God’s  people – drawn through the characters of the Red Dragon, a Woman, and her Male Child (Jesus). Summed up: the Dragon tries to eat the Child and kill the woman… but he doesn’t accomplish either.  Instead, the Child becomes a king who rules next to God, and the woman is hidden in the wilderness and waiting for her son to rescue her.  

John then moves into a cosmic battle in heaven, where Satan is defeated and thrown down to earth because they are not strong enough for God and his angels.  There is rejoicing because, “The accuser of our brethren has been thrown down. I saw Satan fall from the Heavens like a lightning bolt.”

Satan can no longer accuse any of us before God because Christ, our king, has tossed him out of his kingdom (vv. 7-10). In verse 11, we are told that we no longer stand accused because “we” have overcome him by “blood” and “testimony”.  Believing wins the Battle as we believe in His Blood (The Blood) and express it through the word of our testimony.