The 'real' reason that the RCC and Masonry don't get along is that Masonry plotted against the RCC. OF course, this was back when the Church was
the master of the Papal States and ran the politics of europe to great effect. Masonry is a liberal organization, and thus, especially in those old
days, was constantly struggling with tyrants, both ecclesiastical and secular.
The stated reason that a member of the RCC can't be a Mason is that, (as far as I understand it) that Masonry is a secular organization promoting
secularism (this of course is from a time when a person who didn't accept church authority could be labled an atheist).
The Carbonari connection is interesting. The Carbonari minimally
had some of their groups radicalized against the church-state. But the fact
that they'd accept master masons directly into their structure doesn't seem to really mean that they were a coal-smeared arm of Masonry. The
culmination of the high degrees of the Carbonari, who, btw, beleived that Jesus was the 'first carbonar' and the exemplar of the order, invovled the
member meeting 'in the hut in the forest' being broken up by Austria soldiers, who'd procede to clobber the members, with revolutionary slogans
being shouted by them. Clearly, a work up to revolution.
But, lets take this in context, this is in pre-risorgimento
Italy, when the Papacy had direct rule over northern Italy, was supported by the
shock troops of the Holy Roman Empire, and the public were aggitating for 'liberal and democratic reform' by having a King, of all things. Different
The Carbonari were only one (primarily Neapolitan I beleive) secret society out of many, and like pretty much any other secret society, had 'ties',
in terms of style and membership, to masonry.
Secret Societies promoting overthrow of The State