People Dilemmas...

So when someone becomes a new believer, he naturally has places to grow..as do all of us on this side of eternity;) To demand instant change in all areas may be too much..and his heart issues are between him and God. But if someone has an issue that he refuses to see as a problem..and you can see it potentially affecting other believers....do you give him grace and wait, or do you lovingly call him out on it? Where's the line? Is it being too overbearing to say "I love you no matter what, but this IS wrong, you ARE making a mistake," or is that appropriate tough love? I tend to feel like truth spoken in love, whether or not someone will accept it, is always right. Especially when one person could lead another into a bad situation. But I don't trust my own wisdom enough to say I'm right. I want to know how to truly love..and not grow foolishly frustrated with people like this. Praying for wisdom and love...