These words of Jesus are sometimes quoted to undermine attempts to name other people's behavior as morally wrong and sinful. "Who are you to judge what other people do or believe," we're told, "since Jesus himself told us not to judge others? Our job as Christians is not to judge people but to love them. That's what Jesus did, right?"
But this is, at best, a half-truth that robs Christians of the capacity to reach any kind of moral discernment about right and wrong, virtue and vice, truth and error. (The irony, of course, is that there is one negative judgment that this half-truth allows for, and that is the judgment that making negative judgments about someone's behavior or beliefs is wrong!)
In his book Introducing Moral Theology: True Happiness and the Virtues, William C. Mattison makes a distinction between making judgments versus judmentalism that rescues us from the performative contradiction entailed by this misuse of Jesus' words. After quoting Matthew 7:1 in the context of a discussion about chastity and nonmarital sex, Mattison writes:
... what Jesus is not condemning is recognizing faults in ourselves and others. The whole point of the Sermon on the Mount, for instance, is to explain how to live in accordance with the kingdom of God, and doing so entails recognizing, especially in ourselves, what actions run counter to that kingdom. In fact, Jesus gives explicit instruction on how to confront a peer whose behavior is damaging herself and the community (Matt. 18:15-17). Thus, judging in the sense of making distinctions about what is good and bad behavior is clearly not what Jesus denounces. Yet being judgmental, in the sense of using such a discussion as a way to demean others or exalt one's self, is surely what must be avoided, according to Jesus. ...
Judgmentalism is not compatible with love. A good stance to adopt in this difficult discussion [of chastity and nonmarital sex] is this: how would you address this topic with your teenage child or sibling who sought guidance from you on when to have sex? What lines would you offer him as to when to know the time is right? Only by refusing to offer any response would you avoid making judgments, and that would surely not be in the teenager's best interest as he seeks guidance. Presumably you would tell him what you think is in his genuine best interest, and encourage him to act accordingly. That would be making a judgment, because you want what is best for him. You would hopefully avoid being judgmental, that is, lording it over him or condemning him if he fails. ... Thus, the most loving thing we can do for others and ourselves on challenging questions such as these is to humbly strive to speak the truth rather than tell people what they want to hear, since the truth is what is genuinely best for people.
Mattison also cites the example of Jesus (the one who purportedly never judges anyone because he loves them so much):
Perhaps the finest example of this judgment vs. judgmentalism distinction is the famous story of Christ and the woman caught in adultery (John 8:1). Christ does not refuse to label her behavior sinful. Indeed, the story ends by his saying, "Go and sin no more." Yet Jesus' primary concern in that story is to stop the woman's peers from self-righteously (in that they failed to recall their own sin) denouncing her, rather than lovingly correcting her, as Jesus himself does.
Looking to Jesus, Mattison reminds us of the critical importance of distinguishing between judgmentalism's condemnation and judgment's correction.
Mattison helps us steer a middle course between the harsh legalism that condemns and throws people away on the one hand, and the permissive tolerance that sanctions a moral relativism that tacitly (if not explicitly) blesses false beliefs and destructive behavior on the other hand. It's a fine line to walk, to be sure. And Lord knows the Church has all too often failed in ways that have been deeply hurtful. But it's also a tragic failure when the Church does not own her call to follow Jesus' example by exercising the moral leadership of right judgment and loving correction.