It is important to understand the difference between being judgmental and discerning truth from error. In Matt. 7:1, the Lord said, “Do not judge lest you be judged.” Then, in verses 2-5 he warns against trying to correct others without first correcting what is wrong in our own lives. If we deal honestly deal with our own hearts, etc., then we have the responsibility to help others. But there is also a warning in verse 6. He said, “Do not give what is holy to dogs, and do not throw your pearls before swine” (vs. 6). How can we know that someone, in their spiritual condition, is like a dog or a pig (i.e., someone who is incapable of appreciating the truth—apathetic, cold, indifferent), unless you judge, discern their character or their spiritual condition?
This passage does not teach that judgments should never be made. In fact, Matthew 7:5 specifically speaks of removing the speck from your brother’s eye. But the Lord’s point is that no one is qualified nor able to do that if they are habitually critical or condemnatory of the specks in someone else’s eye when they themselves have a plank—a hyperbole for effect—in their own eye. Such are not truly interested in righteousness, only in playing spiritual king of the mountain.
So, as in selecting elders and deacons for office (1 Tim. 3), judgment is sometimes needed, but those making the distinctions (krino, judge, means “to distinguish” and thus “to decide”) must first be certain of their own lives and their motives. We need to ask questions like, Am I doing this to show how much I know? Am I trying to play spiritual king of the mountain? Do I think I am better than they are because I know something they do not know? These are some of the logs that we must remove from our own eyes (hearts). We are not judging people when we discern behavior or beliefs that are clearly unbiblical. For an excellent passage on having a judgmental spirit versus a discerning spirit, read Paul’s teaching on the problem of doubtful or questionable things in Romans 14.
Furthermore when seeking to help others, we must exercise care to discern their spiritual appetites and do what would be appreciated and beneficial. We need to test the waters, so to speak. Ask a question in a non-threatening way to see if they might be open to discussion. “Would you be interested in what the Bible has to say about astrology?” We do this because one should never entrust holy things (what is sacred) to unholy people (dogs; cf. “dogs” in Phil. 3:2) or throw ... pearls to pigs. Dogs and pigs were despised in those days. This is one of the reasons the Lord spoke in parables. He did so to hide truth from the indifferent and to reveal it to those who were hungry and prepared.
Finally, remember that the ultimate issue is not seeking to get people to change their behavior, but come to know and believe in Christ. This includes biblical repentance, but in a salvation context, that means recognizing their sinful condition and need and turning from their sources of trust (religion, human will power, cultism, astrology, etc.) to trust in Jesus and His death for their sin. It does not mean cleaning up their lives and then trusting in Christ. Only Christ can change lives in a way that is significant.