This world can be a tough place to live and we can fall into its habits. Even though Christians are suppose to live apart from worldly things, sometimes we all need another Christian for one thing...
Calling another Christian out can be a rough thing. I mean it can feel like it is not your place, but sometimes other Christians need it. Scripture says, "Brothers, if anyone is caught in any transgression, you who are spiritual should restore him in a spirit of gentleness. Keep watch on yourself, lest you too be tempted. Bear one another's burdens, and so fulfill the law of Christ," in Galatians 6:1-2. Not only is this telling us that we should be there for our brothers and sisters and help them with their burdens and restore them, but it also tells us how to do it. You must always remember that no one is perfect (not even yourself) so always be gentle when you are correcting someone. Do it out of love and do not be harsh.
However, when you are restoring one of your brothers or sisters, not only must you be gentle but you must be sure you are blameless too. Not perfect, but blameless in whatever it is they are struggling with. I cannot go and correct someone on what they are doing when I myself am doing it too. Scripture also says, "why do you see the speck that is in your brother's eye, but do not notice the log that is in yours," in Mathew 7:3.
I am not saying that you should constantly run around correcting everyone else on everything that they are doing wrong. People struggle with things and so will you. You have to use your judgement on when and how to approach them. Just remember to always be there for your brothers and sisters when you need them and do not be afraid to correct them when they truly need it.