The devil has no right to a place in our lives. Here he will find a "No Entry" sign. Our bodies "are a temple of the Holy Spirit" (1Cor 6:19).

Paul says: 

"Nor give place to the devil."

Eph 4:26

In other words: Do not let the devil occupy areas in your life that you want only for yourself—things that cannot bear the light of day. Giving place to the devil is to leave a door ajar for sin and possibly also for illness. If we give him a finger, he quickly takes the whole hand. 

The devil cannot do anything against us if we do not give him a place. 

"Therefore submit to God. Resist the devil, and he will flee from you."

James 4:7

All rooms within us belong to Jesus. We do not want any "secret rooms" for ourselves. Jesus lives in our hearts. We have given him all the keys to all rooms, and God's peace then reigns in our hearts. 

"And the peace of God, which surpasses all understanding, will guard your hearts and minds through Christ Jesus."

Phil 4:6