Better Not To Tell About Serious Sin?

From Dave Armstrong

Q: If you have to know that a sin is “grave” in order for it to be mortal (full knowledge and consent) then why would you want to tell someone that something is grave matter? Wouldn’t their ignorance of grave matter keep them from committing mortal sin and thus not endanger their salvation?

A: It's important that people are aware of what is a grave sin. Even if not knowing that sin x which has been committed is a grave matter and objectively a mortal sin (but not subjectively due to ignorance), a person is still harmed, as sin does no one any good and ultimately leads to spiritual death (Rom 6:16, 23; 7:11; 8:2; Jas 1:15; 5:20). Therefore, people ought to know what is considered serious sin, because habitual committing of such sins will eventually exclude one from heaven (see, e.g., Rev 21:8: "But as for the cowardly, the faithless, the polluted, as for murderers, fornicators, sorcerers, idolaters, and all liars, their lot shall be in the lake that burns with fire and sulphur, which is the second death" [RSV] ).

Pax et bonum