Even attempting to use the word 'factual' in a theological discussion is ludicrous!

The Catholics will be surprised to discover that they are not Christians.  You would think that the guy buried in the Vatican would have some slight claim to be a follower of Christ, at least.  Not to mention the one supposedly buried in St. Mark's in Venice.  

All the "Pieces of the True Cross" and most of the other Saints' relics scattered about Europe are most likely bogus, but there seems to be at least some contemporary history for those two.

Whether Catholics are Christian illustrates the problem.  

Theology and doctrine define a 'Christian'.   Then you kill eight million people in the Thirty Years War to make sure that your definition is followed.

380 years later, you want to reopen those wounds and kill off the Catholics because they are not Christians, I guess.