Let there be no filthiness (obscenity, indecency) nor foolish and sinful (silly and corrupt) talk, nor coarse jesting, which are not fitting or becoming; but instead voice your thankfulness [to God].
Ephesians 5:4 (The Amplified Bible)
Apostle James, by the inspiration of the Holy Spirit, rightly stated in his epistle that the tongue, though small, has great power and one sign of spiritual growth is the ability to bridle one’s tongue.
The use of profane words like the f-word, the s-word and several others, though spoken with little or no restraint in the world should not be heard among Christians.
One might question who or what determines whether a word is offensive or not, however, what matters is that they are and are recognized by users of the language as socially offensive. The Bible describes them as obscene, indecent and filthy.
Blessings and curses cannot proceed from the same source. It does not work that way. Our words as Christians should glorify God and minister grace to our hearers. You might not be in the best of moods and that’s understandable, but self-control is part of the fruit of the regenerated spirit.
The use of such words generally shows debasement, rudeness or lack of respect. These are totally contradictory to what learn of Christ who teaches us to love our neighbours.
If you use profane words as a Christian, consciously decide to stop it and work on controlling your speech, by the power of the Holy Spirit who is at work in you.
If you are a Christian, then you should act and speak like one.