Judging vs Judgmental?

I have had an interesting experience over the last couple of weeks. As I was talking with a friend about the hurt that had been caused her by a Christian 'brother', I became really frustrated that he (who is a Christian) could bring the name of Christ into such disrepute, claiming, in the aftermath, that he doesn't care about his reputation (a fact which I seriously question anyway!)

He has become hurt over people's judgment of him and his actions. I've really struggled throughout this saga to know how to react to this guy. Part of me, wants to encourage him to pull up his socks, stand apart from the world, and act more like the man God would have him be. The other part of me says it's not my business ... But that doesn't 'sit' right either...

My question is ... As Christians, do we (do I?!) have the right to lovingly challenge people about their behavior if it doesn't line up with what God asks of us in the Bible? And if we do, what does that look like? Or, should we just leave them be, and accept that we all, as humans fall short of God's standards? We all have planks in our own eyes, right?