Am I Sick Because I Left a Door Open to the Devil?
Probably not.
Plenty of sicknesses have NOTHING to do with opening a door to the devil. The sicknesses are around because we live in a fallen world. You can’t assume that you have a stuffy nose because you left a door open to the devil so that he could put it on you.
We don’t see Jesus lecturing people about leaving doors open to the devil when He healed the multitudes.
However, it is possible under the New Covenant to open a door to the devil. This is proved by Ephesians 4:27, where you are commanded to give no place (or opportunity) to the devil. Thus, it must be possible to NOT “let the devil in,” but it must also be possible to “let the devil in,” depending upon your actions.
The most blatant case is sexual sin. The Bible warns that your flesh can be consumed if you commit adultery (Proverbs 5:8-11). Homosexual activity also leads to bodily trouble (Romans 1:26-27). So sexual sin certainly opens a door so that you can get one of Satan’s sicknesses.
Alcoholism and drug abuse also open the door to physical problems, and you can probably think of some other sins that will lead to physical trouble.
It makes sense that if you ALLOW the devil a place, he will take it. That is why YOU have to actively resist him (James 4:7, 1 Peter 5:8-9) rather than passively allowing him to stay and bring his baggage.
One interesting angle here is that Paul warned that if you sow to the flesh, you will reap FROM THE FLESH (not the DEVIL!) corruption (Galatians 6:8). Sin carries built-in consequences without any direct involvement from the devil. You’re still forgiven for whatever the sin is, but that doesn’t mean that there will be no consequences in this life. The only way to avoid the consequences is to avoid the sin.
You should expect that God will show you any areas where you are not operating in the proper mindset (Philippians 3:15). When He shows you such an area, repent! That will close the door to whatever consequences your improper mindset might bring on. The good news is that if you have left a door open to the devil, you can close it and keep it shut from now on!
And there’s even more good news. You can receive healing for something even if you got it by opening a door to the devil! Don’t you suppose that there were people in the crowds who had opened the door to the devil, but Jesus healed them anyway? You can be healed even if you opened a door, but if you’re wise, you’ll close that door so that you won’t get sick again. Jesus healed a man who had sinned, but He told him to sin no more so that he would not get even sicker in the future (John 5:14). God is so merciful that He is willing to heal FOOLS who got themselves sick through their sin (Psalm 107:17-20).
The important thing is to let the Lord reveal you where you are “off” (if anywhere). Otherwise, you can go on an introspective “witch hunt” for where you left a door open to the devil and have it turn out that you actually didn’t leave ANY door open – you just got something that is part of fallen creation.
See also:
Does Satan Have the Legal Right to Afflict Me If I Open a Door to Him?
What Did I Do to Deserve This Sickness?
Sickness as Chastening and Judgment in the New Testament