Judging others is a moral necessity. You need to know whether or not you want to associate with an individual, how else are you to come to that conclusion without forming an opinion based on your observations/experiences?

"The precept: 'Judge not, that ye be not judged' . . . is an abdication of moral responsibility: it is a moral blank check one gives to others in exchange for a moral blank check one expects for oneself.

There is no escape from the fact that men have to make choices; so long as men have to make choices, there is no escape from moral values; so long as moral values are at stake, no moral neutrality is possible. To abstain from condemning a torturer, is to become an accessory to the torture and murder of his victims.

The moral principle to adopt in this issue, is: 'Judge, and be prepared to be judged.'

The opposite of moral neutrality is not a blind, arbitrary, self-righteous condemnation of any idea, action or person that does not fit one’s mood, one’s memorized slogans or one’s snap judgment of the moment. Indiscriminate tolerance and indiscriminate condemnation are not two opposites: they are two variants of the same evasion. To declare that 'everybody is white' or 'everybody is black' or 'everybody is neither white nor black, but gray,' is not a moral judgment, but an escape from the responsibility of moral judgment.

To judge means: to evaluate a given concrete by reference to an abstract principle or standard. It is not an easy task; it is not a task that can be performed automatically by one’s feelings, 'instincts,' or hunches. It is a task that requires the most precise, the most exacting, the most ruthlessly objective and rational process of thought. It is fairly easy to grasp abstract moral principles; it can be very difficult to apply them to a given situation, particularly when it involves the moral character of another person. When one pronounces moral judgment, whether in praise or in blame, one must be prepared to answer 'Why?' and to prove one’s case—to oneself and to any rational inquirer."