By Unlike the times in church history marked by persecution, our churches often contain people who claim to be Christian, perhaps even more mature than the rest of us, but who are not really Christian at all. We can have great unity with true believers from all walks of life, but what do we do with those ‘Christians’ who teach things that are not really Christian, and who practise things that are not holy, and who cause division among believers over issues other than Truth and Godliness? On the one hand they seem to be the most misguided, unholy, and divisive, but on the other hand, they teach with such confidence, live with such freedom, and seem so discerning that we don’t know how to think about them and their awkward influence on the church and reputation in the world.
There are three clear dividing lines in Scripture that we as believers in Jesus Christ can maintain to clear up any confusion about ‘Christians’ who are not really Christians.
The first category of required divisions is the category of false doctrine.
I appeal to you, brothers, to watch out for those who cause divisions and create obstacles contrary to the doctrine that you have been taught; avoid them. For such persons do not serve our Lord Christ, but their own appetites, and by smooth talk and flattery they deceive the hearts of the naive.
Romans 16:17-18
When another Christians teaches something very strongly that is not that clearly and strongly taught in the Scriptures handed down by Jesus’s Apostles, then do not be intimidated. Know that they are not really Christians. Avoid them.
The second category of required divisions is the category of immoral lifestyles.
But now I am writing to you not to associate with anyone who bears the name of brother if he is guilty of sexual immorality or greed, or is an idolater, reviler, drunkard, or swindler—not even to eat with such a one. For what have I to do with judging outsiders? Is it not those inside the church whom you are to judge? God judges those outside. “Purge the evil person from among you.”
1 Corinthians 5:11-13
Christians repent of sin; a Christian who boasts of sin is therefore not really a Christian. Separate from those who claim to be Christian, but excuse sin, boast in sin, minimise sin, and ignore sin.
The third category of required divisions is the category of divisive individuals.
Avoid ‘Christians’ who teach false doctrine and separate from ‘Christians’ who promote immorality. If there is a ‘Christian’ who causes division for any other reason, then separate from him too.
As for a person who stirs up division, after warning him once and then twice, have nothing more to do with him, knowing that such a person is warped and sinful; he is self-condemned.
Titus 3:10-11
Don’t feel guilty or spiritually incomplete because of ‘Christians’ who seem more knowledgable than the Bible or more holy than Jesus. If a ‘Christian’ feels strongly about his better views or your bad traditions, but Scripture does not actually teach those Truths or condemn those practise, then have nothing to do with that person, knowing that such a ‘Christian’ is not really a Christian.
Keep up the distinction between a Christian and an unbeliever, and make it clearer every day.
– C.H. Spurgeon