“Again you have heard that it was said to those of old, ‘You shall not swear falsely, but shall perform your oaths to the Lord.’ But I say to you, do not swear at all: neither by heaven, for it is God’s throne; nor by the earth, for it is His footstool; nor by Jerusalem, for it is the city of the great King. Nor shall you swear by your head, because you cannot make one hair white or black. But let your ‘Yes’ be ‘Yes,’ and your ‘No,’ ‘No.’ For whatever is more than these is from the evil one” (Matthew 5:33-37).
An unrighteous mouth is a heinous thing. Since it is out of the abundance of the heart the mouth speaks (Matthew 12:34), an unrighteous mouth tells the following ugly truths about the heart from which it flows:
- There is a serious lack of love and reverence for God and holy things. Using sacred language in meaningless ways is a telltale sign of disrespect.
- There is a woeful lack of love and reverence for truth. If you are only concerned about being truthful when under oath or in some extraordinary circumstance, your valuation of truth is abjectly pitiful. The truth is to be esteemed as most precious (Proverbs 23:23; John 8:32, 14:6; 1 Peter 1:22), not trodden under foot like good-for-nothing salt or priceless pearls given to pigs.
- There is a blatant lack of love for your fellow humans. No one—including you—likes to be lied to. The second greatest commandment is to love your neighbor as yourself (Matthew 22:39), and the Golden Rule is to treat others as you want to be treated (Matthew 7:12). To lie to another is an egregious violation of both these significant commands.
An unrighteous mouth is an attempt to cover a heart in league with Satan with lips which sound like they are in league with God.
An unrighteous mouth is hideously ugly.