Secrets & Sin

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We all know what a secret is, and we all know that when information is given to us privately, revealing it publicly is moral matter, which is only Just in certain narrow circumstances, and sinful in other circumstances, even to the degree of being a mortal sin.

Using the knowledge of a secret, such as an explicit statement that information shared privately is not meant to be public, even without a promise to not use the secret, is unjust when it infringes a right or harms a person without necessity. It is against Charity to do that.

Stealing or unduly using the secret of another is a mortal sin by nature, violating Justice and Charity. The sin is aggravated by the greater damages or displeasure caused to the victim.

Being entrusted with the personal information of others that are not meant to be public is a moral responsibility not to divulge or use that information, especially when it causes harm against one's neighbour. And it is of graver importance not to use secrets for evil ends, such as reviling and other evil speech. If one does not understand this, then it is something one can study, and that would be virtuous if done for a good end. (Moral Theology: A Complete Course, by McHugh & Callan, 2408-2417)

But one need not know the theology to understand what is against Charity. Charity is love, and if one has it, it covers many sins, as written: But before all things have a constant mutual charity among yourselves: for charity covereth a multitude of sins. (1 Peter 4:8)

Charity is a supernatural virtue, infused into our soul by God, by which we love God above all for His own sake, and our neighbour as ourselves for the love of God.  (Catechism of Pius X, On Charity, Q 42)