Varieties of Judgement

A well known dictum from the Bible (I believe it's a verbatim quotation, but I do not know the book, chapter, or verse, so I stand to be corrected) states "Judge not lest ye be judged."

What does it mean "to judge." For example, regarding the story about the teenagers who beat a homeless man to death while others watched, I am inclined to say that I should not judge the others who watched. Yet can I at the same time say that watching without assisting the man was wrong (a statement that is a judgment about right and wrong) and still be consistent? I think so, as long as I am clear about what sense of judgment I mean. Here are the following senses I can identify.

• Judgment as to the truth or falsity of facts
• Judgment as the choice between at least two possibilities
  
• Judgment as to rightness or wrongness of a given act
• Judgment as moral condemnation or as moral approbation

I am inclined to say only the latter meaning is intended by the Biblical verse. Still, obeying such a verse--if one is so inclined--strikes me as particularly difficult.