Romans 16:17 - Matthew Poole's English Annotations on the Holy Bible

He shuts up the Epistle with a seasonable admonition, which he reserved to the last, that it might be the better remembered: it is, to beware of those that cause divisions and offences. By the former, some understand those that corrupt the doctrine of the church; by the latter, those that violate the discipline thereof: others refer divisions to faith, and offences to manners. There are that like neither of these distinctions, but, think he only cautions them against church dividers; and mentions scandal or offences as the effect or fruit of church divisions. He seems to aim more especially at those who, together with the Christian faith, did obtrude upon believers the ceremonies of the law, as necessary to salvation; of these he often complains as enemies to the gospel and cross of Christ: see Galatians 1:7 Philippians 3:2,18,19 Tit 1:10. Contrary to the doctrine which ye have learned; i.e. that you have learned from those that first taught you and converted you to Christ: q.d. You have been instructed in the true doctrine of Christ; and there are some that would innovate and teach another doctrine, that broach opinions that are contrary, or, at least, beside the doctrine which is pure and apostolical, and so make divisions and factions amongst you: of such as those he speaks what follows. And avoid them; here are two precepts with respect to innovators and church dividers. The first is, that they should be marked. The word signifies such a marking, as a watchman useth that standeth on a tower to descry enemies; he marketh diligently all comers, and giveth notice accordingly, for the safety of the place. The second is, that they should be avoided, or declined: the like counsel is given, 2 Thessalonians 3:6,14 1 Timothy 6:3-5 2 Timothy 3:5 Titus 3:10 3 John 1:10. The sum is, the church should excommunicate them, and all sound Christians should turn away from them, and shun their society, that they may be ashamed.