Thomas Aquinas

“ Not every disobedience is sin against the Holy Ghost, but only that which obstinacy is added: for it is not the contempt of any obstacle to sin that constitutes sin against the Holy Ghost, else the contempt of any good would be a sin against the Holy Ghost, since any good may hinder a man from committing sin. The sin against the Holy Ghost consists in the contempt of those goods which lead directly to repentance and the remission of sins. ”

“ The first sin of our first parent, from which sin was transmitted to a men, was not disobedience considered as a special sin, but pride, from which then man proceeded to disobey. Hence the Apostle in these words seems to take disobedience in its relation to every sin. ”

“ Further, a person is said to be disobedient when he does not fulfil a superior's command. But superiors often issue so many commands that it is seldom, if ever, possible to fulfil them. Therefore if disobedience were a mortal sin, it would follow that man cannot avoid mortal sin, which is absurd. Wherefore disobedience is not a mortal sin. ”

“ And since it seems to point to a certain excellence that one be not subject to another's command, it follows that disobedience arises from vainglory. But there is nothing to hinder mortal sin from arising out of venial sin, since venial sin is a disposition to mortal.
Reply to Objection 3: No one is bound to do the impossible: wherefore if a superior makes a heap of precepts and lays them upon his subjects, so that they are unable to fulfil them, they are excused from sin. Wherefore superiors should refrain from making a multitude of precepts. ”

“ First, on the part of the superior commanding, since, although a man should take every care to obey each superior, yet it is a greater duty to obey a higher than a lower authority, in sign of which the command of a lower authority is set aside if it be contrary to the command of a higher authority. ”