Christianity does not teach not judging. It teaches judging after you judge yourself. If you judge someone who steals, but you do that as well, then your judgement is hypocritical, thus contradictory and void. If however you judge yourself and see no blemish in that particular virtue, then you are free to judge those who can’t do as you do.
The judgement may even teach them how to do otherwise, or even help them realise that people are noticing their contradictory actions and words. Essentially, judge only after you have judged yourself able to judge without contradicting yourself – which is the core of ethics.
‘Judge not, that ye be not judged.
For with what judgment ye judge, ye shall be judged: and with what measure ye mete, it shall be measured to you again.
And why beholdest thou the mote that is in thy brother’s eye, but considerest not the beam that is in thine own eye?’ – Matthew 7:1-3 (KJV)
That is to say:
You shall be judged by the same standards that you judge others. Avoid hypocrisy. Be consistent. Measure yourself by the standards which you measure others by. Judge yourself by the standards which you judge others by.