For with what judgment you judge, you will be judged

Matthew 7:2
For with what judgment you judge, you will be judged; and with the measure you use, it will be measured back to you.

This is truly a scary statement. The consequence is great, yet the sin itself is so common that everyone of us have done it. We have judged others, often we don't even know we are doing it. The objective problem is that we too are guilty of various offenses, hence we are in no position to judge. Yet it is human nature to judge. The best thing is simply not to judge others at all. Note however, that there is a distinction between judging people and criticising the work or deeds of others. Sometimes there may be a fine line - so we just need to be careful. Ultimately, our focus should be towards God.