'Warn' in the Bible

For by the grace [of God] given to me I say to everyone of you not to think more highly of himself [and of his importance and ability] than he ought to think; but to think so as to have sound judgment, as God has apportioned to each a degree of faith [and a purpose designed for service].

I urge you, brothers and sisters, to keep your eyes on those who cause dissensions and create obstacles or introduce temptations [for others] to commit sin, [acting in ways] contrary to the doctrine which you have learned. Turn away from them.