You write often about eternal security, OSAS. Scripturally, I agree with you. But if we are eternally sealed when we are born again and the devil cannot snatch us from Christ’s grasp, what is his end game, just our misery?
Satan, being temporarily in control here (1 John 5:19), has made trouble of one sort or another a certainty in our lives (John 16:33). Also, the combination of our free will and our sin nature causes us to make bad choices that can give him limited access to us from time to time.
I think he makes use of these factors to prevent us from attaining the victorious life God intends for us. And that keeps us from being a good example for unbelievers who might otherwise be attracted to the Christian life.
If the Church as a body was able to fully apply all the promises the Lord made to us, we wouldn’t be able to build buildings big enough or fast enough to house all the converts.