Tut, tut, Jckstraw. As is typical you seem to conveniently overlook those pesky EOC and OOC who are not Protestants and who exist in enormous numbers and who have never had anything remotely resembling a dogma of the assumption. I think you may discover, if the numbers are tallied, that your church, numerically, is in the minority on this issue.
However, whether one person or a billion people earnestly believe or disbelieve this dogma does not establish its veracity or lack thereof. It is a dogma conceived within the Catholic Church in 1950 which ought to say something. The fact that this "truth" eluded other denominations as dogmatic, absolute truth and continues to elude them for so long must mean something, don't you agree?