Between the warmth of the names and the warmth of the final greetings, Paul inserts something sharp. It is not out of place. It belongs exactly here — because the community he has been describing throughout this letter can be destroyed, and the way it is most commonly destroyed is from the inside.

"Now I urge you, brethren, keep your eye on those who cause dissensions and hindrances contrary to the teaching which you learned, and turn away from them" (Romans 16:17).

The instruction has two parts: watch, and turn away. Not engage endlessly, not argue indefinitely, not extend hospitality to every teacher who arrives claiming the name of Christ. Watch — identify who is causing dissension contrary to the teaching already received. And then turn away from them.

The teaching that was received is the standard. Paul is not telling the Romans to evaluate new teachers by their personality or their reputation or the size of the audience they carry with them. He is telling them to measure what is taught against what they already know. The doctrine received through the apostles is the benchmark. What contradicts it, however it is packaged, is to be avoided.

The reason follows: "For such men are slaves, not of our Lord Christ but of their own appetites; and by their smooth and flattering speech they deceive the hearts of the unsuspecting" (Romans 16:18). The false teacher is identified not merely by wrong doctrine but by the combination of wrong doctrine and right presentation. Smooth speech. Flattering language. The approach calibrated to disarm. The unsuspecting person who has not learned to measure teaching against the received doctrine is exactly the target the false teacher aims at.

Paul's confidence in the Roman congregation is real: "I want you to be wise in what is good and innocent in what is evil" (Romans 16:19). That is a specific kind of wisdom — deep knowledge of what is good, genuine ignorance of the sophistries of what is evil. The congregation that has spent its energy learning the good, thinking about the good, practicing the good, does not need to become expert in the range of theological errors available. It needs to know the truth well enough that the counterfeit is recognizable on contact.

The promise closes the warning with a horizon: "The God of peace will soon crush Satan under your feet. The grace of our Lord Jesus Christ be with you" (Romans 16:20). The crushing of Satan under the feet of the saints is language from Genesis 3:15 — the seed of the woman bruising the serpent's head. Paul applies it to the community here and now. The false teacher who works division is not operating independently. He is a point of entry for something older and more malevolent. And the God who will crush the enemy under the feet of His people is the same God who brought them out of sin, filled them with His Spirit, and is carrying them toward glory.

The grace of the Lord Jesus Christ be with you. Not a throwaway closing. A declaration of what actually sustains the community through all the warnings and all the dangers: the grace that was announced in chapter one, argued through to chapter eleven, and lived out in chapters twelve through fifteen.