One of my biggest concerns when I talk about sin, is the idea that someone will get the wrong idea about me in the process. When I call out sin, I don't do it from a position of "judgment". I do it... from an educational standpoint?
Just because I denounce sinfulness doesn't mean that I'm perfect, or that I myself have fully and undoubtedly 100% repented from what I'm denouncing. On one hand, it feels hypocritical (Matthew 7:3-5) to call out behaviors for which I myself am responsible, but on the other hand, it feels even more wrong to keep silent about things that I know are wrong, when somebody could potentially benefit from my warning. For instance, a smoker could still warn a non-smoker about cigarettes, even if the smoker him/herself hasn't quit yet, because s/he still understands the dangers of cigarettes. And so it is with me. I'm in NO position to teach people "with authority", that is, the way Jesus taught, but I still understand that sin is wrong, and so I still try to warn people against it. I just never want to give off the impression that I'm perfect. I'm not. I'm not being "holier-than-thou". I'm still learning, just like everybody who has ever taken advice from me.