If a person you know 'swears like a sailor' or its 'chronically rude to waitresses or a sales person or blatantly makes fun of church or our Savior . . those would be important clues. Keep your eyes open to make assessments as well as listen with your ears while praying for answers. I'm not saying you cannot be friends with such a person because Scripture states 'if possible, so far as it depends on you, be at peace with all men." Romans 12:18. Maybe you can influence them for the good!
