As a Bible teacher, I find that there is a clear line between judging a person, and judging doctrine. I am not to judge another, but I can judge doctrine (teaching.) In fact, if someone is not preaching sound Biblical doctrine, the Bible tells me to “mark them,” and avoid them. That is not judging them as a person, that is an admonition to others to keep them safe. The Amplified Bible says: “I appeal to you, brethren, to be on your guard concerning those who create dissensions and difficulties and cause divisions, in opposition to the doctrine (the teaching) which you have been taught. [I warn you to turn aside from them, to] avoid them.” (Romans 16:17 AMP)
As a “for instance,” Joseph Prince is the primary teacher in the world today of what I call “Greasy Grace,” an un-Biblical doctrine. If you are warned that his doctrine is not sound, and that it is is deceiving the church, that does not mean you are condemning him as an individual, it is simply a warning that his deceptive, demonic doctrine is hurtful to the Body of Christ. We should “mark them” and avoid them… and pray that the veil of deception is lifted from their heart and mind.