This excerpt from the Bible Expositor and Illuminator is such a powerful piece on corrupt speech that I felt the urge to share it. It servis a warning to Christians and unbelievers alike.
Corrupt Speech (Romans 3:13-14) As Thomas Schreiner notes, "The universal dimension of sin is nowhere more evident than [in] human speech." The evil in a person's heart inevitably comes out in a person's speech. Here Paul, (the writer of the book of Romans), drew upon Psalms 5:9, 140:3 and 10:7 to picture this aspect of human depravity. The comparison of people's throats to an open sepulchre or grave, likens their speech to the stench of decay. Although it may not always be evident, their speech flows from an unclean heart and has a corrupting effect on others.
The tongues of sinners are purposely used to deceive others. Flattery and lies are crafted to lead people astray and promote self-interest. Their speech is pictured as the deadly venom of asps or vipers, spiritually poisoning people with their words.
Finally borrowing from Psalms 10:7, Paul describes their mouths as "full of cursing and bitterness." (Romans 3:14). It is not just on rare occasions that they spew forth curses and evil words; their mouths are filled with such speech.
A clean heart is the key to clean speech (Matthew 12:34-35). Yet even believers find it hard to break sinful habits; and unwholesome and evil communication can come out in an instant. Our tongue is perhaps the most deadly weapon any of us will ever wield. Undoubtedly, this is why the Bible has so much to say about controlling our speech. By so doing, we become a source of blessing rather than destruction, and we save ourselves much grief.
Source: Bible Expositor and Illuminator, Summer Quarter 2016, Published by Union Gospel Press, Cleveland, Ohio. page 77