Why can't you answer my question? I'm not trying to trick you; it's very simple.
If one attends an 'una cum' mass, is it a mortal sin? Y/N? If so, why? Show me from canon law, from a papal pronouncement, etc.
You seem to imply that those priests who say an 'una cum' mass are not intrinsically wrong but it is wrong based on circumstances. What circumstances are those? Just the fact that they mention the pope's name, therefore they are praying 'in union' with him (and his errors)? Look, i know the argument. What I want to know is - show me where the Church has ever taught this, based on the una cum prayer ALONE.
Actually, I have answered you, but you didn't understand it.
I said it was not intrinsically
evil. Let me clarify.
Let me give you an analogy in normal times about the meaning of that. It means that something is likely an occasion of sin to the average person, so, in general, it is forbidden as a mortal sin, because to knowingly put oneself in a circumstance of near occasion of sin, is itself a mortal sin even if the person ends up not sinning mortally....because he willfully took a chance of sinning grievously.
But there could be individuals to whom it is not a near occasion of sin. Catholics are not good judges of whether it is or not, so it should be a confessor, or higher Church authority to decide. For instance, a Catholic, by canon law, would be excommunicated for even having an heretical book on his bookshelf. However, permission or dispensation could be given in a case of necessity to a learned Catholic to be able to read such a book.
Basically that is what a "dispensation" is. It is a circumstance that is dangerous to the average person, and so forbidden to all, UNLESS a special permission is given based on evaluating the person and circumstance.
So, to apply this again...it is a near occasion of sin for the average person to attend an R&R Mass because of the magnetic danger of being attracted to whatever the priest is associated with.