Letting others sin venially or telling them a sin is mortal?

[FCS]

If I knew something was a mortal sin and a family member did not know that that thing was a sin, would I have to tell them that it was a mortal sin?

If I did not tell them that it was a sin, would I be guilty of sin?

Ex-not telling someone that it is required to do Penance on Fridays

 

[guanophore]

If I knew something was a mortal sin and a family member did not know that that thing was a sin, would I have to tell them that it was a mortal sin?

If I did not tell them that it was a sin, would I be guilty of sin?

None of us is in a position to know if another person is guilty of mortal sin.
We can educate people about what the Church considers to be grave matter, but whether they are willfully rejecting God only God can know their hearts.

There may be some circumstances in which you may be guilty for participating in the sins of others, but in general, living a sanctified life yourself is a better way to evangelize others than focusing on their wrongdoings.

 

[crenfro]

One of the works of mercy is to admonish the sinner. If I see a family member approaching a sinful act it would be an act of charity to warn them. It could be a sin of omission for me to not warn them, in fact.

However, part of the definition of mortal sin is to know it’s wrong and to go ahead and do it anyway, so this would not be a mortal sin.

 

[Rob2]

@FCS , you ought to follow the advice given above by @guanophore .

 

[guanophore]

One of the works of mercy is to admonish the sinner. If I see a family member approaching a sinful act it would be an act of charity to warn them. It could be a sin of omission for me to not warn them, in fact.

Indeed this is one of our obligations. Fulfilling it can be a challenge, as one must also remove the logs from one’s own eye before attempting to take out the speck in the eye of the family member. No one knows our faults and shortcomings as those closest to us, with whom we live or have grown up.

 

[Annie]

It is best to approach these things carefully. For example, is the family member in a position of authority over you? Would the family member be receptive to such admonishment from you? How interested are they in following Church teaching? Etc.

Sometimes it is best to bring the information out in a way that is not admonitory, to share information one has learned rather than to “scold,” esp if the family member is older than you are.