The scripture does not say they overcame him by their testimony only. It says they overcame him by the word of their testimony. The word of their testimony was the Word. They spoke the Word of God. It took two things to overcome the devil.
It took the blood of the Lamb (Jesus) and the saints speaking the Word of God.
The way Jesus overcame Satan during His temptation was by using the Word. He said, "It is written." "And Jesus answered and said to him, 'Get behind Me, Satan! For it is written, You shall worship the LORD your God, and Him only you shall serve'" (Luke 4:8).
We need to know about the Word, but we also need to understand that it takes the blood of the Lamb and the Word to overcome.
Is it possible that as New Testament Christians we can be correctly speaking the Word of God in the name of Jesus and not see results? What is our response when we do not see the results? Do we just speak the Word louder and start telling God how we are in faith and all we are doing for Him, when we're really missing the component of the blood?
They overcame by the blood of the Lamb and by the Word of their testimony.
By hearing and confessing the Word and by being cleansed by the blood, we enter into salvation. The devil will do everything in his power to discredit the Word and devalue and dilute the blood.
"And war broke out in heaven: Michael and his angels fought with the dragon; and the dragon and his angels fought, but they did not prevail, nor was a place found for them in heaven any longer. So the great dragon was cast out, that serpent of old, called the devil and Satan, who deceives the whole world; he was cast to the earth, and his angels were cast out with him" (Rev. 12:7-9).
The devil was cast to the earth and his angels with him. The scripture says he is a deceiver. He deceived one third of the heavenly host into thinking that somehow he could overthrow God. They believed in a lie. The devil works the same way today.
You would think over the centuries men would have become wise to the lies of the devil. Many have, but many people continue to believe his lies. Jesus said in John 8:31-32, "If you abide in My word, you are My disciples indeed. And you shall know the truth, and the truth shall make you free."
"You are of your father the devil, and the desires of your father you want to do. He was a murderer from the beginning, and does not stand in the truth, because there is no truth in him. When he speaks a lie, he speaks from his own resources, for he is a liar and the father of it" (John 8:44).
Excerpt permission granted by Larry Ollison Ministries