“…full and truthful knowledge that the chosen act is a serious sin…” .
Where is this quote from? I did a search of the Catechism and could not find such wording.
The Catechism states:
1859 Mortal sin requires full knowledge and complete consent. It presupposes knowledge of the sinful character of the act, of its opposition to God’s law. It also implies a consent sufficiently deliberate to be a personal choice. Feigned ignorance and hardness of heart do not diminish, but rather increase, the voluntary character of a sin.
1860 Unintentional ignorance can diminish or even remove the imputability of a grave offense. But no one is deemed to be ignorant of the principles of the moral law, which are written in the conscience of every man. The promptings of feelings and passions can also diminish the voluntary and free character of the offense, as can external pressures or pathological disorders. Sin committed through malice, by deliberate choice of evil, is the gravest.
If one thinks incorrectly that the matter is grave but it is in reality not, there is no mortal sin. The matter must be grave, in fact, not in fancy
Since morality is always and everywhere dependent on the state of mind of the moral agent we cannot speak of “objective morality.”
Yes, we can. Objective morality does exist.
It follows from above that the Church does not teach that there are any objective mortal sins; only objective evils. Objective evils, or intrinsic evils always and everywhere have bad effects. However, one who commits an intrinsic evil does not necessarily sin, since sin has subjective components known only to the actor and God.
This makes no sense to me. of course there are objective mortal sins. Are you advocating relativism?