Judging def #1: "deciding who we think a person is on the inside based on what we see of them (actions, behavior etc)"
Judging def #2: "Looking down on other people based on what we see of them (actions, behavior etc)"
I am for and against judging and here's why.
For ALL have sinned... Just because my sin isn't as obvious as someone else's doesn't mean I don't have it. I think we should all try our best to live without sin, but no matter how hard we try we will ALL struggle with it until the day we meet our Lord. Who are we to judge who is a worse sinner than others? God is no respecter of persons and neither should we (James 2:9). We are SINNERS - pretty self explanatory title. Why do we act so shocked and appalled (and secretly delighted) when we hear about a fellow sinner sinning?
I think we should "judge (def #1)" others and be discerning about who we associate with or become close to lest we fall into OTHER sins than we already struggle with. I think "judging" (def #2) is just to feel better about ourselves even though our righteousness is as filthy rags. By rolling our eyes at other people's sin we are saying "wow, glad I'm not THAT much of a sinner." But we are. You're a sinner, I'm a sinner, we all need Christ.
I think rebuking, sharpening, edifying others in a Biblical manner would be judging #1 and acting on that judgement because you have genuine concern and care for someone.
I think watching/rebuking someone's sin from afar, gossiping about it, being generally aghast and just shaking your head because you can't believe the type of sin someone else struggles with is judging #2 and is, I believe, very unChristlike.