You will hear all sorts of things; "Matthews" means they are left-handed, "Mathews" means they are right handed, "O'Brian" is Irish but "O'Brien" is Scots, "Brown" is northern, "Browne" is southern . . . Most of those are false.
There are 3 Jewish surnames, Levi, Cohen and Cantor, all with a dozen spelling variations. There are a couple of Christian Surnames, "Christian" being one (Fletcher Christian, from Mutiny on the Bounty, for instance) and "Saint ---", where "---" is a saint's name being another hundred or two.
The rest of the surnames in the world can be Christian, Jewish, or Druid, for that matter.
Sometimes there is a nugget of truth in the story about spelling; ---sen is usually Danish and ---son is usually Norwegian or Swedish, where "---" is Lars, Paul, John, Johan, Ole .... Wilken is German, Wilkin is English, usually. I have never seen anything that makes a correlation between spelling and religion; just spelling and original language.
Almost always, though, spelling variations emerge because people didn't spell consistently. One of my lines is Wyssman. Anna Wysmann had 12 children, and I have marriage licenses for 8 of them. They spell her maiden name 7 ways, about evenly split between man and mann there at the end, and Wys, Wyss, Weis at the start. Same lady, staunch Lutheran all her life, ---man and ---mann both.
I usually tell beginners that if they haven't found the surname they are working on spelled at least 6 ways, they haven't been looking hard enough. "Pack", for example, is only 4 letters, and is a common noun as well as a verb. I have found Pack spelled Back, Pack, Peck, Pak, Pock, Puck, Park, and Pork.
My favorite is a man who came to the USA as Henrich Kesselburg and died Henry Castleberry, having used (or been recorded with) Kessel, Kassel, Cassel, and Castle for the first part, burg, berg, bury and berry for the last part.
My most recent was a family of Cullins, who were down as Cullin, Cullen, Cullins and Cullens, then repeat with "Coll" instead of "Cull".
> I have not been able to find any topics that discuss this or give you a straight answer.
That's because the story you heard was a myth. If you pick a country, ethnicity or language, you will probably be able to find something about surname patterns. "ez", for instance, means "son of" in Spanish, so "Martinez" means "son of Martin". There are prefixes or suffixes that mean "son of" in most European languages.
30 years of genealogy