We must learn to differentiate between what is the devil and what is the fleshly nature of believers who are not walking in the spirit. Generally, a believer who is manifesting wrong behavior is not demonized, but yielding to the sinful desires of the flesh. The believer will know when they are in disobedience to God because they will already know by the Spirit and Word what the right behavior should be, but are unwilling to do it. This is not the devil, this is rebellion in the heart of the believer which needs to be repented of immediately. When someone is under the power of the devil, (demonized), they will not necessarily know of the devil’s presence unless the Holy Spirit discloses it.