I know that slander and railing are wrong as we see in the word of GOD. Remember GOD is love and when you speak evil of someone GOD may take pity on that person and take vengeance on you. This is something I have known for some time as I see it written in the word of GOD so I try my best not to rail or slander another believer even if I do not agree with them. However, I may still try and speak the truth about what they have done or said that I disagree with and yes this at times has made me feel bad about saying it. Anyway, we need to be careful but not too careful that we do not even warn others about someone who may be leading people in the wrong direction. Keep in mind we still need to love those who are doing that but leave the vengeance up to GOD. That does not mean we need to be friends with them. I am passing this on so you don’t make the same mistake I make or made. We can speak the truth in love. Either love to warn others or love to try and correct those in error.
Here is a Comment on another site that goes into more details about what I am saying and in a way I am replying to that comment but also trying to help you.