To be fair, the treacherous Mormon massacre of over 100 American men, women and children, after accepting their surrender on terms, took place a little more recently.
1857, not 1555.
Arguably on the direct instructions of Brigham Young.
The worst massacre of white Americans by white Americans in our history.
Personally, I don't find this disqualifying for Mitt. But it is perhaps relevant to recognize that in Mormon history the extreme fanaticism and resultant violence found in the history of most "Christian" denominations is a good deal more recent.
And, like most of the other arcane things of MORMONism, were basically covered up.
Thanks to Al Gore, who invented the Internet, facts are being widely distributed about LDS, Inc. and many of the adherants of the things taught by Joseph Smith, etal, are exTREMELY upset about it.
You statement might be valid if mormonism were in any fashion a Christian denomination - it is not so your statement fails.