Evil communications corrupt good manners.
Another way of saying this is, “Bad company corrupts good character.” In other words, by hanging around with the wrong crowd you can get into all kinds of trouble. Be very careful who your friends are. They may not be all that bad in themselves. But when you are around unsaved people, their lack of Christian moral standards can have a degrading effect on the way you view things. Eventually things that used to be wrong to you don’t seem so bad after all and you will allow things in your life that are not right for a Christian to practice. Ask the Lord to help you find Christians to be friends with.