How must the church handle those who cause divisions and oppose the doctrine that we have been taught?

Romans 16:17, Romans 16:19

They must be excluded from the fellowship and avoided altogether. The disruption of the unity and community of faith is initiated when people sow division about what one may and must believe. When they challenge the apostolic tradition in this way, cracks are likely to develop in the foundation of the church. For this reason the church must take a dismissive attitude towards all who seek to introduce a different doctrine. The church must not greet them in the same way they are called to welcome Phoebe (Romans 16:1–2), for example. On the contrary, Paul says, 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 (Romans 16:17). The Greek makes it clear that these divisions and the obstacles are, in the first place, directed against established doctrine. Paul is therefore not speaking about a quarrel that has arisen in general (in conflict with the tradition that teaches love), but about the fact that the doctrine itself, which the readers have been taught, is being questioned and becomes the subject of opposition. People who cause such divisions do not build on the foundation laid by the apostles and do not adhere to their doctrine. It is striking that Paul is speaking about a doctrine that you have been taught, although he himself has not preached in Rome. This points to the fact that at that time there already was a general proclamation of the basic truths of the doctrine of faith. This is what the apostle Paul refers here to. The readers are expected to judge every teacher that comes along using that doctrine as standard, and they must not even greet anyone that brings another doctrine, nor must they have communion with such a person but rather avoid him (compare also to 2 John 1:9–11). Paul here lays the foundation for a church federation that preserves true doctrine and excludes all who oppose it, and encourages the church in Rome to embrace this same watchful attitude towards heretics by praising her for her faithfulness: For your obedience is known to all, so that I rejoice over you, but I want you to be wise as to what is good and innocent as to what is evil (Romans 16:19).¹