IMO, it has to do with attitude and purpose.....
JUDGING is condemned in the Bible. it stems from a "holier-than-thou" attitude that seeks to put down others (and thus make self look better by comparison); it seeks to hurt. This is condemned because it is the anti-thesis of love and because it ignores the reality of our own sinfulness, our own fallen nature.
CORRECTING is mandated in the Bible. We are to apply the Law. But it stems from great humility (for we too are sinners who live and breathe ONLY because of God's mercy, grace and forgiveness) and with the purpose of HELPING our brother, to help them up (not put them down). There's an old Christian saying that goes something like this: "The church is not a country club for those who egotistically CLAIM to be goody-goody but a hospital for those who know they are sick." We're in this together.... and we need the help of each other.... and that involves both Law and Gospel (properly applied).
That's my half cent....
- Josiah
With respect, I think judging is critically important. It's far from condemned in the Bible - what is condemned is unrighteous judgment. Many pull Matt 7:1 out of context and merely quote "judge not, lest ye be judged yourself" but if it's taken in the context of the next few verses it's clear that Jesus isn't telling us not to judge, he's telling us to judge righteously. He condemns those who pick at specks in the eyes of others while they have logs in their own eyes (the unrighteous, or hypocritical, judgment) but goes on to say how we should remove the log from our eye
so that we can see clearly to remove the speck in our brother's eye (emphasis mine). There's no sense that we shouldn't be removing the speck, merely that we should remove our own log first.
We cannot correct someone unless we have considered their actions and judged them to be sinful. We cannot reject the teaching of the false christs and false prophets that Jesus warned us about unless we test their teaching against Scripture and judge it to miss the mark.
As you quite rightly say we should do so in love - there's a world of difference between loving correction and being haughtily judgmental.