Okay, so here we go....
I'm walking down the sidewalk. The weather is nice, the night air cool against my cheeks. I stop at the sight of a group of teenagers hanging out a couple of yards away from me. They're smoking pot. Before I can turn and go the other way, I spot one of my friends at the edge of the group, laughing with one of the kids whose got a cigarette between their fingers.
I can't help my jaw from dropping. I didn't think my friend would ever be hanging around people like that. I walk up to her and tell her that. She glances at her "friends," then sneers at me. "People like what? You think they're more sinful than you are because they smoke pot everyday and you don't, Miss Goody-Two-Shoes?"
Oops. I didn't mean to say it like that. I didn't mean to say "people like that." I just meant I didn't realize she hung around people that were addicted to marijuana. They aren't a people group. They're just people, like me. The only difference between me and them is that they choose to live in sin day after day. "I'm sorry. I didn't mean they were somehow more sinful than me. They're not. I just mean... well... they're choosing to harm their bodies." I say.
"So what? They're their bodies. Who cares what they do?" She moves away from them to talk to me without being overheard.
"Your body is a temple of God. You know that."
"Chill. Stop judging me for hanging out with them. It's not like I'm smoking or anything."
But I can deduct the consequences of hanging around people like that. I can clearly see that her actions are wrong. She shouldn't be around something or someone that could tempt her into trying a smoke or two. Just for fun. I'm not judging her, I'm calculating her outward actions. Can I say that she doesn't think smoking is wrong? No. I don't know what goes on in her heart. Only God does. That's His department. He judges the heart. "But I, the LORD, search all hearts and examine secret motives. I give all people their due rewards, according to what their actions deserve" (Jeremiah 17:10 NIV).
I can only "judge" the outward actions. Never the inward motives. That's what John 7:24 means when it says, "Stop judging by mere appearances, but instead judge correctly." Clearly it is sin to judge just by what people look like, but when someone is living in sin, and you can see that they are so you speak your observation out loud to them, concerned for their spiritual life, that is NOT judging.