Part of what drives the hypothesis that Shakespeare was Catholic is the extent to which Catholic views of religion and of our relationship to God infiltrate his plays. (For examples of a discussion of this type, see
“How Catholic was Shakespeare?”.) Also fueling this discussion is the evident difficulty in finding an evidence trail for the actual writer: a Catholic, it is thought, would need to be secretive in a climate of rampant Protestantization (so to speak).
However, familiarity with Catholic themes could also be part of the make-up of any well-educated person of that time. A writer committed to good writing does not shy from utilizing themes even though they be alien to his own particular sensibilities. Just a few moments ago, I ran across a hypothesis that a nobleman named Edward de Vere could be the author. He was a man of wide learning, close to government, educated in law, well-traveled, and broadly experienced in many ways sometimes uncannily similar to matter depicted in various plays and sonnets (
1). Various reasons are suggested for considering “Shakespeare” to be a pseudonym. And, noblemen were discouraged from writing (
2).
De Vere was almost certainly not a Catholic, given how close he was to the corriders of power in Protestant England. His son Henry became a noteworthy Protestant. However, de Vere still benefited from familiarity with Catholic points of view, even if he had no sympathy for them himself. The importance of proximity is evident in the fact that today the Catholic elements of Shakespeare plays often sail right past modern viewers, who consider a decent death one where the family is not too dispersed, who consider decent dress one in which the midriff is not completely exposed–unless one is on the beach, and who consider a decent engagement one in which sex is “practiced” “safely”, and “not right away, of course”.
Of course I don’t claim to know whether Edward de Vere was the author of Shakespeare plays; I am just mentioning the possibility.