How we should respond to those who appear to teach theological error? Is it right to criticise them, and if so, in what way and on what grounds? In Mark 9, for instance, the apostles came across someone, not from among their number, who was casting out demons in Jesus name. They tried to stop him and complained to Jesus.

Jesus rebukes them for their narrow, sectarian attitude. He is not advocating the tolerance of false teaching, but insisting that it is not necessary for his followers to all wear the same badge or belong to a particular group in order to be on His side.

In the New Testament, there is a spectrum of teaching on how we should relate to people with whom we disagree. At one end of the spectrum are passages like Mark 9, which warn us not to be too exclusive. We should warmly accept people who labour for the Lord Jesus in different ways, or unusual places, or who use unconventional methods to our own. We should not censure them just because they're "not one of us".

However, at the other end of the spectrum are passages such as Galatians 1:6-9 where the condemnation of false teaching could not be stronger nor clearer.

There are several other passages which could be placed along the spectrum between Mark 9 and Galatians 1, which help us understand our responsibility, such as the following:

Even though the gospel is being preached from poor motives by Paul's opponents, Paul rejoices that at least Christ is being preached.

Paul exhorts the Roman Christians not to be hyper-critical of each other, but show generosity and tolerance in disputable matters.

Part of the responsibility of an elder is to silence those who promote false doctrines and idle speculation. (see also Titus 1:9-11)

In dealing with opponents, Christians must resist the temptation to be resentful or unkind. We must gently correct those who are in error and instruct with the hope and purpose that the Lord would bring opponents to repentance.

Here Paul is jealous for the Corinthians because he is very worried that they are in danger of being deceived and of accepting a false gospel.

What follows is a more detailed list of what the Scriptures teach us about how to respond to those who propagate theological error.

"Woe to you, teachers of the law and Pharisees, you hypocrites! You travel over land and sea to win a single convert, and when he becomes one, you make him twice as much a son of hell as you are. "Woe to you, blind guides! You say, 'If anyone swears by the temple, it means nothing; but if anyone swears by the gold of the temple, he is bound by his oath.' You blind fools! Which is greater: the gold, or the temple that makes the gold sacred?......."Woe to you, teachers of the law and Pharisees, you hypocrites! You are like whitewashed tombs, which look beautiful on the outside but on the inside are full of dead men's bones and everything unclean. In the same way, on the outside you appear to people as righteous but on the inside you are full of hypocrisy and wickedness......You snakes! You brood of vipers! How will you escape being condemned to hell? Matthew 23:15-17, 27-28, 33

"Woe to you, because you are like unmarked graves, which men walk over without knowing it." Luke 11:44

You belong to your father, the devil, and you want to carry out your father's desire. He was a murderer from the beginning, not holding to the truth, for there is no truth in him. When he lies, he speaks his native language, for he is a liar and the father of lies. John 8:44

Then Peter said, "Ananias, how is it that Satan has so filled your heart that you have lied to the Holy Spirit and have kept for yourself some of the money you received for the land? Acts 5:3

"You are a child of the devil and an enemy of everything that is right! You are full of all kinds of deceit and trickery. Will you never stop perverting the right ways of the Lord? Acts 13:10

Then Paul said to him, "God will strike you, you whitewashed wall! You sit there to judge me according to the law, yet you yourself violate the law by commanding that I be struck!" Acts 23:3

They claim to know God, but by their actions they deny him. They are detestable, disobedient and unfit for doing anything good. Titus 1:16

He who does what is sinful is of the devil, because the devil has been sinning from the beginning. The reason the Son of God appeared was to destroy the devil's work. 1 John 3:8

2. We must warn of and watch out for false teaching

"Watch out for false prophets. They come to you in sheep's clothing, but inwardly they are ferocious wolves. Matthew 7:15

Jesus answered: "Watch out that no one deceives you.......For false Christs and false prophets will appear and perform great signs and miracles to deceive even the elect - if that were possible. Matthew 24:4-5, 23-26

I know that after I leave, savage wolves will come in among you and will not spare the flock. Acts 20:28-29

I urge you, brothers, to watch out for those who cause divisions and put obstacles in your way that are contrary to the teaching you have learned. Keep away from them. For such people are not serving our Lord Christ, but their own appetites. By smooth talk and flattery they deceive the minds of naive people. Romans 16:17-18

Don't have anything to do with foolish and stupid arguments, because you know they produce quarrels. 2 Timothy 2:23

Warn a divisive person once, and then warn him a second time. After that, have nothing to do with him. Titus 3:10

For such men are false apostles, deceitful workmen, masquerading as apostles of Christ. And no wonder, for Satan himself masquerades as an angel of light. It is not surprising, then, if his servants masquerade as servants of righteousness. Their end will be what their actions deserve. 2 Corinthians 11:13-15

The Spirit clearly says that in later times some will abandon the faith and follow deceiving spirits and things taught by demons. 1 Timothy 4:1

The coming of the lawless one will be in accordance with the work of Satan displayed in all kinds of counterfeit miracles, signs and wonders, And in every sort of evil that deceives those who are perishing. They perish because they refused to love the truth and so be saved. 2 Thessalonians 2:9-11

But even if we or an angel from heaven should preach a gospel other than the one we preached to you, let him be eternally condemned! As we have already said, so now I say again: If anybody is preaching to you a gospel other than what you accepted, let him be eternally condemned! Galatians 1:8-9

The wrath of God is being revealed from heaven against all the godlessness and wickedness of men who suppress the truth by their wickedness, Romans 1:18-19

Now the Bereans were of more noble character than the Thessalonians, for they received the message with great eagerness and examined the Scriptures every day to see if what Paul said was true. Acts 17:11

Do not conform any longer to the pattern of this world, but be transformed by the renewing of your mind. Then you will be able to test and approve what God's will is - his good, pleasing and perfect will. Romans 12:1-2

Dear friends, do not believe every spirit, but test the spirits to see whether they are from God, because many false prophets have gone out into the world. 1 John 4:1

Test everything. Hold on to the good. 1 Thessalonians 5:21

With Mark 9 at one end of the spectrum and Galatians 1 at the other, it is not always easy, when faced with error, in the heat of the moment, to work out the appropriate response, especially given our fallen nature and the deceit of Satan. However, respond we must, loving our opponent, but hating his error, praying for his repentance while distancing ourselves from both it and him, and warning other believers to do the same.