Can unbelievers cast out devils?
What did Jesus mean when He said, "Depart from Me, I never knew you"?
A quick look into these things:
It is possible to be a believer in Jesus, cast out devils and on the day of judgment hear Jesus tell you, "Depart from Me I never knew you" (Matthew 7:21-23).
A Jewish priest by the name of Sceva had seven sons who were not followers of Jesus. They decided one day to visit those possessed of evil spirits that they might expel them using the name of Jesus. Here is the account, "And the evil spirit answered and said, “Jesus I know, and Paul I know; but who are you?” Then the man in whom the evil spirit was leaped on them, overpowered them, and prevailed against them, so that they fled out of that house naked and wounded" (Acts 19:15-16).
From this passage it is very clear that unbelievers cannot cast out devils.
Furthermore, Jesus said that if Satan cast out Satan then he is divided against himself . . . but if I with the finger of God cast out devils, no doubt the kingdom of God has come upon you (Luke 11:18-20).
This brings us to the next question: WHAT DID JESUS MEAN WHEN HE SAID "I NEVER KNEW YOU"?
We mentioned earlier, it is possible to be a believer in Jesus, cast out devils and on the day of judgment hear Jesus tell you, "Depart from Me I never knew you" (Matthew 7:21-23). It is possible to use the name of Jesus to expel demons, to even call Him Lord and recognize Him as Lord and yet Him not recognize you. It is possible to be very involved in religious activity and yet Jesus tell you on judgment day, "I never knew you". It is not only possible but Jesus said that He will tell many, not a few, but many, "Depart from Me I never knew you".
Let's look at the context of those words, "Not everyone who says to Me, ‘Lord, Lord,’ shall enter the kingdom of heaven, but he who does the will of My Father in heaven. Many will say to Me in that day, ‘Lord, Lord, have we not prophesied in Your name, cast out demons in Your name, and done many wonders in Your name?’ And then I will declare to them, ‘I never knew you; depart from Me, you who practice lawlessness" (Matthew 7:21-23).
So, if only those who believe in Jesus are able to cast out demons then why does Jesus tell those who expelled demons in His name "I never knew you"? What does He specifically mean by the words "never knew"? Were not all things made through Him so that without Him there wasn't anything made that was made (John 1:1-3)? If all things were made through Him then wouldn't He at least know the names or recognize the people there before Him on that day? What is that day? It is the day of judgment! If He is Judge and King and Lord and He doesn't know this multitude of people, then how can He pronounce any eternal sentence upon them or make any judgment whatsoever?
One explanation for the words "never knew" is found in what Paul wrote to the church of Corinth, "If anyone loves God, this one is known by Him" (1 Corinthians 8:3). What does it mean to love God? "This is the love of God that we keep His commandments" and "If you love Me, keep my commandments" and "He that has My words and obeys them, it is he that loves Me" (1 John 5:3, John 14:15, 21).
So when Jesus tells this multitude, "Depart from Me I never knew you" we must admit that they are believers who are able to expel demons in His name, believe on Him as Lord, recognize the authority He has over evil spirits and so on, but they "practiced lawlessness". They never truly loved God and therefore He never truly knew them to love Him.
Another reading from this passage to the Corinthians is, "But if anyone loves God [with awe-filled reverence, obedience and gratitude], he is known by Him [as His very own and is greatly loved]. It is not that Jesus doesn't know who these people are, for even the very hairs on their heads are all numbered and He knows so much about them that He is able to judge them according to their works, but He never knew them intimately. He never knew them to be disciplined learners, faithful followers of what He taught them or His image (character) to be formed in them.
The New Covenant promise is that our sins and lawless deeds will be remembered no more (Hebrews 8:12), that He will subdue our iniquities and cast our sins into the depths of the sea (Micah 7:19), and as far as the east is from the west so far will the Lord remove our transgressions from us (Psalm 103:12).
On the other hand, Scripture also tells us that if a righteous man walks away from the ways of God to live a life of sin that God will remember his righteousness no more (Ezekiel 18:24), and Jesus promised that if the church of Sardis repented, held fast, would be watchful for Him and overcome, that He would not remove their name from the book of life (Revelation 3:1-6). We can be sure that Jesus does not warn us of impossibilities. If He told the church that their name would not be removed from His book of life if they received His warning and repented, then we can be sure that if they didn't obey Him that He could remove their names from the book of life and be cast into the lake of fire (Revelation 20:15).
Assuredly, as God no longer remembers the sins of those who believe in Christ, who repent, turn from their sins to live for and to obey Him, even so He no longer remembers the righteousness of those who turn away from the path of life, the path of righteousness, from following Jesus Christ.
Even as Jesus is able to remove our sins so effectively that it is as if they were never there, so He is also able to erase our name from His book of life, so that it is as if it was never recorded. When Jesus says to those believers who expelled demons in His name, "Depart from Me I never knew you" we must conclude that Jesus never intimately knew these people even though they were able to cast out devils, called Him Lord, operated in spiritual gifts, etc. They had faith, even works, but no faith expressing itself in loving obedience.
Hear the warning of the apostle,
"For if, after they have escaped the pollutions of the world through the knowledge of the Lord and Savior Jesus Christ, they are again entangled in them and overcome, the latter end is worse for them than the beginning. For it would have been better for them not to have known the way of righteousness, than having known it, to turn from the holy commandment delivered to them" (2 Peter 2:20-21).
Conclusion: The great commandment is to love the Lord your God with all of your heart, soul, mind and strength.
Jesus will say to many on judgment day, "I never knew you; depart from Me you, who practice lawlessness".
What is lawlessness? "Whoever commits sin also commits lawlessness, and sin is lawlessness" (1 John 3:4). Practicing lawlessness means to make a practice of sin.
"Practice lawlessness" does not mean to stumble into sin or to lose a battle fighting the good fight of faith from time to time. It means to have a light hearted attitude towards sin that presumes upon the mercy and grace of God and therefore is emboldened to sin willfully, and it also means to have a casual care for the things of God so that one's religious activity or involvement is treated as common instead of holy and sacred.
Those who practice lawlessness often have a theology suited to the hardness of their hearts, so that their carnal appetites can, without interference, be satisfied.
Those who practice lawlessness often justify their errors using the mistakes, stumblings, and weaknesses of others. "Didn't King David commit adultery with Bathsheba yet remain a man after God's heart"? "Wasn't Balaam a prophet of God, who prophesied of the coming of the Messiah, yet He was greedy for financial gain and prestige"? "Didn't the apostle Peter dissimulate when James brought other Jews with him to visit"?
Many today believe in Jesus and do many wonderful works yet Jesus does not know them because they do not love God, they do not obey Him (John 14:21-24).
If you are reading this, are convicted, and fear that you have made a practice of sin, I encourage you to go sit at the feet of Jesus by going to a secret place in your home, and confess your errors and faults, and seek Him for forgiveness of your sins and the grace to be a faithful disciple.
From 2 Corinthians 7:9-11 we learn that worldly sorrow produces repetition, leading to death but that godly sorrow produces true heart level repentance, leading to salvation.
Worldly sorrow makes a practice of sin but godly sorrow will always produce authentic change.
Cut off every worldly influence and hindrance to your relationship with God.
Shut the doors of your ears to every word spoken by family, friends, preachers that would seduce you into weakness and keep you bound up in sin. The truth will set you free. The Son will make you free indeed.