But the Lord is faithful, who will establish you, and guard you from the evil one.
Now Paul is commanding them that you really separate yourselves from the disorderly brothers.When Paul wrote to the church in Corinth, he said we are not to have fellowship with those who are drunkards, who are committing fornication, who are living after the flesh, who claim to be brothers in Christ. He said you can't just exclude yourself from mixing with everyone who does these things. In other words, you live in the world, you can't get out of that. But with those that say they are brothers, don't eat with them. Don't fellowship with them if they are walking disorderly. He is saying now the same thing, only commanding them in the name of Jesus that you withdraw from these disorderly people.