Don't want to restart an argument here but the term Infidel, meaning unfaithful (from latin) does tend to be associated with religion, and was particularly used as a slur on Muslims by Christians. 'The Infidel hoarde', etc, because it also means un-faithful, as in, they have no faith [in a Christian God].
I always took Vito's reference to Sollozzo as an 'Infidel' to mean that he considered him to possess lower values than Vito and his peers, because he had so embraced non-Christian Turkish culture. This coming from a traditionalist catholic I mean. For instance, technically speaking Sonny also practiced infidelity towards Sandra, but Vito didn't call him an Infidel, he just told him off for "all that comedy you're playing with that young girl"

The phrase "make your bones" is usually used loosely to mean, "prove yourself," rather than to signal your formal induction into the Mafia as a "made man." Henry Hill in "Goodfellas" acknowledged that he could never be "made" because he wasn't 100% Italian on both sides. When he said that "Air France made me," he meant that it made his reputation as a good earner and a guy to be reckoned with. Moe Green was Jewish, so he couldn't be "made." When he shouted to Michael Corleone, "I made my bones when you were going out with cheerleaders," he probably meant that he had proved himself by killing at an early age. When Clemenza gave Rocco a ".22 snub nose" and said, "You make your bones on Paulie today," I think he meant that Rocco would rise in the family after whacking Paulie. I'm guessing that Rocco had already been formally "made" by that time.