“Do not think that the Mussolini family are all that good as Catholics (although Benito did arrange for the Vatican to be sovereign).”
The 1929 Vatican Concordat was mainly for political reasons. BM was an atheist from what I’ve heard. Keep in mind that he had once been active in left-wing politics.
To be fair, many people identify with a religion for political or cultural reasons without seriously following its teachings. This is particularly a common practice in Europe.
It was a lot less true in Italy 80 years ago.