They accidentally signed one yonks ago in a South African who they presumed was a raving reformation-head. Quietly transferred him when they found out he was, in fact, a filthy Papist. Souness did unbelievably well to drag them out of their Protestants-only days, never mind those loonies burning their STs. Celtic gave up any Catholics-only policy and were signing Protestants pretty soon after they were founded, and almost definitely before Hibs. The early Hibs/Hearts aggro is not to be underestimated. Hibs used to be the Catholic/Irish club in Scotland.