“In general I agree, but I think there are exceptions. Penance assigned in confession is the obvious example - it is inherently sinful not to do an assigned penance. Liturgy would be another matter. If the priest were to command that the people in the pews on the left approach communion before those on the right, then it would be a sin to disobey (without good reason). However, if he were to command me to stop dating a certain woman, just because he thinks she’s bad for me, and no other reason (eg. our marital statuses), then it would not be inherently sinful to disobey. I am struggling to think of any occasion, apart from penance, when it would be inherently sinful to not follow a priest’s command to me on a personal or even spiritual matter - even if he is correct, and the matter involves sin. He can withhold absolution for a just cause, but even then if I don’t do his required action (eg. stop living with my girlfriend) then my sin is not one of disobedience. I think that the Church does not give priests such authority.”
The post from Edmundus1581 seems to contradict your post. For if we can avoid some non-immoral advice from a priest then either it is wrong that you should not avoid at least one non-immoral piece of advice or the thing that the priest is doing in the above post is immoral. Which one is it do you think?
Also, when a priest commands someone to do something (I’ve never actually seen it happen so I must ask to prepare myself), then it is obvious to the common sense that he is making a command and there are no jargon words that one has to know in order to know that he is making a command?