Is the pope a Catholic?
A humorous response to a question that the speaker feels would obviously be answered in the affirmative. A: "Are you going to the party tonight?" B: "Is the pope a Catholic? Of course I'll be there!"
is the Pope a Catholic?
People say Is the Pope a Catholic? to mean that the answer to a question is obviously yes. `You know how to find it?' Leaphorn asked. `Is the Pope a Catholic?' the taxi driver said. Note: This expression is used humorously.