God is the potter, and Christians are his clay (Jeremiah 18:4 / 2 Corinthians 4:7). And he is shaping you into the likeness of Jesus, using all of life to do it. That’s the idea of Romans 8:28-29. But when you go against his guiding hand, God has to break you to remake you. And God may use the devil to break a believer down.
Maybe you’ve experienced this. Everything seems to upset you. You try and try, but things just go wrong, and you can’t seem to get a break. It seems like awful is amplified all over your life. It’s like you’re fighting a ghost, whose arming your enemies.
Now sometimes, God is allowing this season to show your faithfulness as an example to others. God may allow an attack to show his strength in your life. You’re wearing the full armor of God. You learn to have the patience of Job. You’re earning rewards in heaven. And those who would accuse you of sin are wrong. You need to stand strong in the Lord despite all the hurt feelings, lack of support, and hard circumstances. And your faith will be vindicated.
However, sometimes you aren’t just fighting your emotions, or people, or systems, or situations. Sometimes, God will allow the devil to invade your life because you have continually opened the door. You have continued in a pattern of particular sin, and God will use the devil to break and humble you. God uses the devil in a Christian’s life to accomplish his purposes. God allows what he hates to accomplish what he loves.