You see, a claim of justification without sanctification is false faith. Even the demons believe that and shudder. Now this is an interesting point. Note this one thing about demons, that they are orthodox. They believe in the right doctrines.
Demons lack sanctification.
Demons don't love God. Demons don't obey God. What demons lack is obedience to God. If somebody claims that he is a Christian but lives like a devil, then we could say that he qualifies to be a demon. That's all there is to it.