All Christians also have a holy obligation. God has called us to be holy (morally blameless), just as He is holy (1 Pet 1:15-16). We are commanded to pursue sinless perfection in every arena of our lives -- our sexuality, our thoughts, our finances, and our words.
But that's where many Christians seem to struggle -- the tongue. Today many Christians think of dirty language as a small sin, an insignificant sin, an innocent sin, a harmless sin. They reason, "It doesn't seem to hurt anybody, so what's the big deal?" True, dirty language is not as bad as murder, or rape, or adultery, or theft, or divorce. But it is a sin, and if you are a Christian, then you are obligated to obey Scripture -- all of it. To repent of all sin -- not just the sins that seem to be harmful to others.
What does the Bible say about cursing? It says to put away filthy language from your mouth (Col 3:9); and no foul language should come from your mouth (Eph 4:29). "Obscene and foolish talking or crude joking are not suitable, but rather giving thanks (Eph 5:3)."
Instead of profanity, God commands us to speak "only what is good for building up someone in need, so that it gives grace to those who hear (Eph 4:29)." "Everything you say and everything you do should be done for Jesus your Lord (Col 3:17, ERV)." Anytime you speak, "let it be as a representative of the Lord Jesus" (Col 3:17, TLB). "Let your speech at all times be gracious (pleasant and winsome), seasoned [as it were] with salt (Col 4:6, AMPC)."
Consider this question. How would Jesus speak? Would He use curse words, and tell sexual jokes? No He would not. And we are called to imitate Him in all we say and do.
Some Christians complain that they want to stop cursing, but it is a hard habit to break. I don't buy it. If I offered you $1 million to go an entire day without cursing, could you do it? Of course you could, or you could come very close. If Jesus came back to earth and hung out with you all day long, do you think you could stop cursing? Yes. You can stop cursing. You can clean up your language.
Dear Christian, if you have a dirty mouth, please repent. Ask the Lord to forgive you for your dishonoring speech, and to give you a clean heart that desires only to exalt the Lord and edify men, "for the mouth speaks from the overflow of the heart (Mt 12:34)."