Why can’t you cuss? It’s not in the bible that says you can’t… you just can’t say his name in vain.

Exodus 20:7 says "You shall not misuse the name of the LORD your God, for the LORD will not hold anyone guiltless who misuses his name.

However, Ephesians 4:29 says this:

29Do not let any unwholesome talk come out of your mouths, but only what is helpful for building others up according to their needs, that it may benefit those who listen. (NIV)

29 Don’t use foul or abusive language. Let everything you say be good and helpful, so that your words will be an encouragement to those who hear them. (NLT)

29Watch the way you talk. Let nothing foul or dirty come out of your mouth. Say only what helps, each word a gift. (MSG)

So I guess the Bible does speak to that.