Whatever comes out of the mouth ;
defiles you
Makes you unclean
Pollutes you
Why does word defile you?
– because whatever comes from the mouth comes from the heart. Every word starts from the heart.
in other words : mouth brings the thoughts in the heart out.
Heart is a storage tank and mouth is the pipe that spills water out.
Example : imagine a water tank and water hose that waters a garden. Water tank ( which is heart) is the source to water the garden . Here garden is your life, your garden has many plants planted in it .. that’s your family, children, spouse, friends, your job, your businesses, your stocks, your assets… etc.. the hose that carries water to the plants is your mouth.
What comes out of your mouth matters a lot because they are directly linked to all that you are and to all that you have. They can either water you good and good fruit or destroy you and defile you and make you unclean .
Bible says Out of the heart come evil thoughts ..
what are these evil thoughts?
they are :
reasonings
Disputes
Designs
Murder
Adultery
Sexual vice
Theft
False witnessing
Slander
Irreverent speech
Every word is born out of thought . So if it’s a negative thought don’t speak it and give life to it otherwise it destroys you.
How do you make suppress a negative thought or turn a negative thought into positive?
confront it with the word of God
Confront it with a praise song
Confront it by submitting your heart and mind to God
When you experience negative thoughts :
Say it out : I have the mind of Christ, I think only that’s pure and edifying to my soul. I put on the mind of Christ .. in Him I am care free and I glorify God with my mouth.. my mouth is a mouth piece of God.. and so forth.

Prayer:
Father in Jesus name : I surrender my every thought to you , fill my heart with your thoughts in Jesus name amen.
Bible references:
It is not what goes into the mouth of a man that makes him unclean and defiled, but what comes out of the mouth; this makes a man unclean and defiles [him]. But whatever comes out of the mouth comes from the heart, and this is what makes a man unclean and defiles [him]. For out of the heart come evil thoughts (reasonings and disputings and designs) such as murder, adultery, sexual vice, theft, false witnessing, slander, and irreverent speech. These are what make a man unclean and defile [him]; but eating with unwashed hands does not make him unclean or defile [him].”
Matthew 15:11, 18-20 AMPC
“He then called the crowd together and said, “Listen, and take this to heart. It’s not what you swallow that pollutes your life, but what you vomit up.” Jesus replied, “You, too? Are you being willfully stupid? Don’t you know that anything that is swallowed works its way through the intestines and is finally defecated? But what comes out of the mouth gets its start in the heart. It’s from the heart that we vomit up evil arguments, murders, adulteries, fornications, thefts, lies, and cussing. That’s what pollutes. Eating or not eating certain foods, washing or not washing your hands—that’s neither here nor there.””
Matthew 15:10-11, 16-20 MSG