By Fr. Thomas G. Weinandy, OFM, Cap., The Catholic Thing - Sin, by its very nature, is a direct attack upon or a violation of some good. For example, lying offends the good of truth; gluttony transgresses the good of proper eating. Now, do some evil acts contravene a good to such a degree that they merit everlasting damnation? According to the Catholic tradition, these acts are termed mortal sins. Let us look at some examples… Fornication and adultery grievously violate the good of marriage and sexuality. While couples, in these sexual acts, may desire to express their love for one another, what they are actually doing is attacking the good of marriage and the sexual acts that pertain exclusively to marriage.