1. A few verses before this passage in Matthew 7:15, Jesus said to beware of false prophets who come in sheep's clothing, but inwardly are ravenous wolves. By outside performance they appear to be sheep, but their inward motives are like wolves-to devour the sheep. These false prophets are not followers of Jesus.It's interesting that these people were not unfamiliar with the things of God, but were probably highly involved in church. This should be a warning that many people think they are Christians, but aren't. Jesus said the proof is in the fruit (Matt. 7:20).
2. Jesus didn't say these people actually performed the miracles and cast out demons, but that they would claim they did these things. "Many will say to me on that day…"
3. Jesus will tell them, "I never knew you…" He won't say, "I once knew you but you lost it." These false prophets never knew Jesus or experienced salvation.
4. Although outwardly they claimed to prophesy, cast out demons, and perform miracles, inwardly they practiced sin. "Depart from Me, you who practice lawlessness."