The video below asks whether Catholics are Christians but really, in its answer, says something much wider about who is a Christian at all, whether Catholic of Protestant.
Interestingly, the answer also makes clear that the answer is not denomination specific per se. Are the Catholics Christians? Essentially, it depends. Are the Protestants Christians? Well, that depends too. But I thought this was a helpful and straightforward answer to a question we were thinking about in our church this Sunday.
You can hear some further details about how we can know we are personally Christian by listening back to our sermon from Sunday here. But, for wider questions of whether Catholics or Protestants are Christians, this is a good place to start.