I think we must got to an often quoted (but not fully quoted) passage in Matthew 7:
Matthew 7:1-6
Do not judge, or you too will be judged. For in the same way you judge others, you will be judged, and with the measure you use, it will be measured to you. Why do you look at the speck of sawdust in your brother’s eye and pay no attention to the plank in your own eye? How can you say to your brother, ‘Let me take the speck out of your eye,’ when all the time there is a plank in your own eye? You hypocrite, first take the plank out of your own eye, and then you will see clearly to remove the speck from your brother’s eye. Do not give dogs what is sacred; do not throw your pearls to pigs. If you do, they may trample them under their feet, and turn and tear you to pieces.
I'd put this passage up as one of the most horribly quoted in the New Testament and probably the Bible as a whole.
Instead of saying, don't judge, the Bible is simply and clearing stating: don't be a hyprocrite about it! It's also giving advice that there are times where you don't waste the pearls (IE: the truth) by just pointing out a sin to an unbeliever. Oftentimes this is accomplished when we confess our own sins instead of going on the offensive to explain their sins to them.
I'd love to talk about this more at the moment, but I must run.