… doesn’t mean that an act for which you’re not culpable is not a sin.
“[I]f a man is ignorant of the fact that something is wrong, and acts in ignorance, he incurs no guilt, provided natural reason was not enough to show him that it was wrong. But while ignorance may excuse the man, it does not excuse the act, which is wrong in itself. If I permitted the act simply because the man is ignorant that it is wrong, then I would incur guilt, because I do know it to be wrong. It is really that painfully simple.”
Quote from A Canticle for Liebowitz by Walter M. Miller, Jr. (italics added), quoted in “Abbot Zerchi and the Dictatorship of Relativism“, by Matthew J. Franck, FirstThings.com (in the context of an article concerning the HHS mandate).