Patti, the verse is from Matthew 7:1-2, and they're Christ's Own words. The idea is don't be a hypocrite. This is the same sermon from which Christ uses the speck/plank illustration. Don't judge your brother for... cheating on his wife if you've got a lady on the side. Don't judge him for being a smoker if you take a few puffs on your lunch break. That kind of thing.
Now, notice, the wording is BROTHER and not NEIGHBOR. I believe this is on purpose, to distinguish our fellow believers from unbelievers. Fix yourself first.
HOWEVER...
The Apostle Paul states we shouldn't judge unbelievers, but those who claim to BE believers in 1 Corinthians 5:12-13. If there's a brother who's involved in the laundry list of sins listed in vs. 5:11, then we have every right to "judge" him and kick him out of the congregation, because "a little leaven leavens the whole lump" (vs. 5:6).
Therefore, to review, we shouldn't judge a brother for a sin we also participate in, however, we are allowed to judge a brother if he's worldly.
So, we shouldn't judge unbelieving worldly people - we have no grounds, they're judged by Yahweh. But we do have authority to judge believers (like the gay priest mentioned above), because Paul goes on in 1 Corinthians 6:2-3, "Do ye not know that the saints shall judge the world? ... Know ye not that we shall judge angels?"
So yes, we are allowed to judge our brethren. The "don't judge" mentality was taken out of context by people who think you're wrong to tell people they're wrong.
