One of the benefits of being in Christ is that He provides a covering over us. This covering He provides from us shields us from the attacks of the evil ones. The enemy is not happy with anything that concerns God and that includes we humans as well. The enemy knows how much we mean to God and that is why he fights anyway possible to prevent us from fulfilling our God given purposes. It is possible for an evil spirit to possess a human.
Matthew 12:45 - Then goeth he, and taketh with himself seven other spirits more wicked than himself, and they enter in and dwell there: and the last state of that man is worse than the first. Even so shall it be also unto this wicked generation.
One of the things that happen when we accept Jesus in our lives is that He sends us the Holy Spirit. And when this Holy Spirit comes He dwells in us. Our body is like an apartment. So when the Holy Spirit dwells in us He prevents every foul spirit from having access to us because we our bodies have already been taken by Him. But for those who lack the person of the Holy Spirit in their lives, they make themselves vulnerable to the attacks of the enemy.
The scripture above is about the scenario of a person that got an evil spirit cast out from him. It says that after that spirit is cast out he is still likely to come around and if it finds that the body of the person he went out from is empty he'll return back with seven others more wicked. This means we should not be empty on the inside except we want to fall victim to the attacks of the wicked one.
1 John 5:18 - We know that whosoever is born of God, sinneth it not. But he that is begotten of God, keep it himself, and that wicked one touched him not.
This is the benefit of when we are in Christ and Christ is in us. And Christ in us restricts us from sinning because sin is another means by that gives the enemy legal ground to lay hold on people.
