Often when the Bible speaks of not judging it has to do with not condemning.  There is, however, a judging that is necessary.  It is a kind of evaluating between good and evil, right and wrong, and better and best.  There is a kind of judging that the church must do in church discipline. There is a kind of judging that seeks to know the difference between true prophets and false prophets by their good fruit and bad fruit (Matthew 7:15-20).  We judge (discern) between spirits: “Every spirit is not from God” I John 4:1-6.   Use your mind.  Listen to the Spirit.  It will help us get through lots of mine fields.  

“Woe to those who call evil good and good evil, who put darkness for light and light for darkness, who put bitter for sweet and sweet for bitter.” Isaiah 5:20 (NIV)