Matthew15:10 Then Jesus called the crowd to him and said to them, “Listen and understand! 11 It is not what goes into your mouth that makes you ritually unclean; rather, what comes out of it makes you unclean.”
Until I became Christian, I didn’t see the need to censor what I said. I would fire off all sorts of curse words. I felt it was possible to be a good guy with a foul mouth since that shouldn’t matter. But when we’re Christian, the spirituality of everything is at play, and we should not be saying ugly words, or belittling anyone, but be uplifting to others with an enriching language.
What is interesting is if we change our hearts to be good people hearts, the need for having to put the brakes on our tongue before we say something nasty is lessened. If we have a good heart and love everyone, we will naturally be saying up lifting things.
There’s a danger when you become more refined in Jesus to look at someone who doesn’t even attempt to tame their own tongue. Someone who curses up like a sailor or Patton seems to be the norm, and we’re not to judge them. We too might have had a period like them before coming to Jesus and Jesus righting our walk.
Also Jesus was talking about being able to eat foods here as some people interpret it.
Ephesians 5:4 Nor is it fitting for you to use language which is obscene, profane, or vulgar. Rather you should give thanks to God.
Colossians 3:8 But now you must get rid of all these things: anger, passion, and hateful feelings. No insults or obscene talk must ever come from your lips.