I think it's long past time Poe's Law hit this thread, so here goes: Hitler never tried to exterminate Messianic Jews.
How about I call myself a Republican For Mohammed (Peace Be Upon Him), gather like-minded people, get funding from Iran (and Russia and China, for some reason) and start holding meetings where I tell members of the US Republican Party that they ought to increase taxes on corporate profits and income above $50,000 per annum, add another tax bracket starting at $150,000 per annum, close tax loopholes, make the first $15,000 per annum tax-free, make many essential goods and services exempt from sales tax, increase sales tax on never-essential luxury items, fund necessary
medical procedures (which does not include breast enlargement beyond a C cup or tooth whitening beyond stain removal, before anyone asks), subsidise public transport between low-income neighbourhoods and areas of job opportunities, increase federal oversight of district, county and state police forces, enforce strict controls on pollution, restrict gun ownership and gun carrying, stand up for intersex, transgender, agender, bisexual, homosexual, polyamorous and asexual people's rights and relationships, stop eating pork, abstain from alcohol, pray towards the Kaaba Stone at noon every day, fast (but not starve themselves silly) for a month every year to gain understanding of what it is to be poor (and not stuff themselves with sweets the minute the Sun goes down every night), cover themselves at least down to the knees and elbows and up to the collarbone whenever they're in public, make sure every child gets full sex education from an atheist with at least an MSc in a related field of biology before the age of 10, make condoms freely available, tax the heck out of fossil fuels, subsidise domestic solar power installations, institute a student exchange program with Iran to foster better international relations and accept Her Royal Highness The Duchess of Cambridge, Princess Catherine, as their spiritual guide?
Can I do that, and expect everyone to accept that I'm as much a US Republican as anyone else on Earth? Can I do that, perform the memorial rites at Bill O'Reilly's funeral and demand that nobody take offence?
There's a rather big difference between "Are Mormons Christians?" and "Are Messianics Jewish?" It has to do with some events around 2000 years ago, which can be summarised as follows:
Some people started preaching that God had taken human form as the Messiah and walked the Earth with the name Jesus. These people were thereafter distinguished from Jews by their belief in this messianic figure
Mormons (claim to) believe that Jesus the Messiah walked the Earth.
Jews, per definition by which Christians are distinct from Jews
If you want to trace the DNA back to the Jew-rassic (sorry!), sure, some of 'em are Semitic. So are Palestinians. Religiously, "Jews for Jesus" are no more Jewish than Hassan Rouhani. The difference is I think he's less of an arsehole.
As for cultural similarity, well, swifts and swallows have some similarities, no?
Oh, Willie McBride, it was all done in vain.