We don’t have to do anything wrong for Satan to attack us. It’s what he does. It’s who he is. The Bible calls him “the accuser of our brothers and sisters” (Revelation 12:10 NLT). And he wants nothing more than to attack those who love Jesus.

Yet often, our own impure lifestyles make us vulnerable to Satan’s attacks. He knows that if he can slip his foot into the door of our hearts through impurity, we’re goners. He’ll trip us up with all sorts of temptations, from pornography to movies to books to advertising—whatever it takes to make us ineffective as representatives of God’s kingdom.

That’s why Paul’s breastplate of righteousness is so important as we battle against whatever Satan throws at us. In Ephesians 6:14, Paul urges believers to stand, “with truth like a belt around your waist, righteousness like armor on your chest” (HCSB).

A Roman soldier going to war would always put on a breastplate to protect his heart. No soldier would dare go to battle without this piece of armor.

Neither should we. Paul tells us that righteousness, or purity of motives, is our breastplate. When we ask God to give us a pure heart and pure motives, we’re putting on that breastplate of righteousness.

Satan fears the person with a pure heart—not the perfect person, but the person who wants to do the right thing and keeps their motives pure. People who pursue purity don’t have to be afraid of him. Satan is afraid of them!

Purity doesn’t mean perfection, though. None of us fit that description. God expects purity of motives, not perfection of action. It means when you do something wrong, you want to make it right. You can’t have God’s blessing on your family, your business, or any other area of your life unless you seriously pursue that kind of purity.

For example, open up your heart to greed, and Satan can get you to cheat on your taxes or make a shady business deal. Leave the door to your heart ajar through pride, and you’ll chase the applause and praise of others rather than the approval of God.

That leads nowhere. Without a pure heart, you’re a pushover for Satan. You don’t have to be strong to stand against Satan’s attacks, but you do need to protect yourself with God’s armor of righteousness.