Romans 3:13-14

"Their throats are open graves;

their tongues practice deceit."

"The poison of vipers is on their lips."

"Their mouths are full of cursing and bitterness."

(v13-14, NIV)

What does it mean to be under sin? Not only that we're all unrighteous and don't even seek God, but all these People being talked about have their throats as open graves. These quotes from Psalms 5 and Psalms 140 don't have anything good to say about these people. These saying also seem to focus around the mouth. It proceeds from throats to tongues then to lips. Being under sin affects what you say. Things that proceed out of you, going from the throat to your mouth, are affected. Talking and things of that nature have to do with you and other people. So, your communication and interaction with other people are affected by being under sin. There is a corruption in such a way that fills your mouth with cursing and bitterness. It's not a good thing and there is nothing pleasant about it.