Calvinism verses Arminianism is NOT an essential. It is a secondary. Salvation by Grace through faith alone is a primary.
When I have more time I will answer you further. But, your point regarding my point on mortal sin backs up my previous point that just because somebelieve it, teaches it, etc., it is not official until it is official. Now if it were in the catechism, I'd say that is more official. If it just something in Benedicts writings as a Cardinal, it isn't official doctrine.
You need to ask a Calvinist if predistination is essential to salvation.
But, your point regarding my point on mortal sin backs up my previous point that just because somebelieve it, teaches it, etc., it is not official until it is official.
You missed my point. The Catholic Church has a doctrine on contraception. Whether someone believes contraception is a mortal sin, or not, has no effect on the Church's doctrine. And the Church won't be changing the doctrine on contraception so that it contradicts the current doctrine.