Revelation 12 is an interesting passage. There is a red dragon, Satan, chasing around a woman giving birth to a man-child who will rule the nations. Fascinating behind the scenes look at God’s plan and Satan’s opposition.
Near the end, John describes the people who defeat Satan by saying (12:11), “And they overcame him by the blood of the Lamb, and by the word of their testimony; and they loved not their lives unto the death.”
They overcome “by” and the word “by” means “because of, or on the grounds of.” They overcome Satan on the grounds of the Lamb’s blood AND on the grounds of the word of their testimony–the fact that they did not value their own lives.
In other words, near as I can tell, it was the blood of the Lamb AND their testimony in completely trusting the blood of the Lamb with their lives.
Sort of makes you grasp what God means by “faith” a little more doesn’t it? Faith without works is dead, y’all.