What is sedition, a sin that is also opposed to charity and to peace?
Sedition is a sin whereby parties of the same people conspire or rise up tumultuously one against the other, or against the established and legitimate authority, whose office it is to guard the well-being of the whole people (XLII.).
Is sedition a great sin?
Yes, it is always a great sin, because humanly speaking there is nothing more excellent and more to be desired than the maintenance of public order, hence the crime of unjust war, and perhaps sedition even more so, is the greatest crime against the well-being of our fellow-men (XLII. 2).
Next - The Catechism of the Summa - SECOND SECTION - A DETAILED SURVEY OF MAN'S RETURN TO GOD - X. OF THE VICES OPPOSED TO CHARITY AND THEIR ACTS: OF HATRED; DISTASTE FOR SPIRITUAL THINGS AND LAZINESS; ENVY; DISCORD; STRIFE; SCHISM; WAR; QUARRELLING (THE DUEL); SEDITION; SCANDAL (L)