Verse explainer
Not a ban on all moral discernment — it's a warning against hypocritical, condemning judgment by a standard you wouldn't accept yourself.
Judge not, that ye be not judged.
BSBDo not judge, or you will be judged.
The plain meaning
Jesus isn't forbidding every evaluation of right and wrong. The very next verses tell you to take the plank out of your own eye so you can see clearly to help your brother with the speck in his (vv. 3-5) — which assumes you will make a judgment, just an honest, self-examined one. And v. 6 ("don't give what is holy to dogs") plainly requires discernment. The target is the censorious, hypocritical spirit that condemns others by a measure it refuses to apply to itself.
The common misreading
What the commentators say
Henry reads it as a warning against rash, harsh, and censorious judging — assuming the worst of others and usurping God's seat — not against the lawful judgment of actions that conscience and duty require of us.
Calvin takes Christ to be condemning the disease of judging that springs from pride and a love of detraction, where people are sharp-eyed toward the faults of others and blind to their own — not the discernment necessary for correction.
Barnes stresses the context: the rule forbids unkind, rash, and unjust censure. Verses 3-5 show the aim is to judge oneself first, then help a brother — not to abolish judgment altogether.
The word behind it
"Judge." A broad verb meaning to separate, decide, or pass sentence. Its compound katakrinō ("condemn") sits nearby in the Gospels. Context fixes the sense: here the force is condemnatory sentence-passing, not the neutral discernment other verses positively command (John 7:24, "judge righteous judgment").
Related verses