Keep Away From Them [Romans 16, TNIV]
I urge you, brothers and sisters, 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. Everyone has heard about your obedience, so I rejoice because of you; but I want you to be wise about what is good, and innocent about what is evil.
The New Testament is full of warnings concerning false teachers and those who would undermine your faith. The litmus test for exposing such people is the gospel message and the truth of the Word of God. May you keep yourselves in the Word each day and hold fast to the truth of God's Word fixing your eyes on Jesus and the gospel message.