Thanks Tdol. That's interesting to know. I never thought that the rule was different for foreign names.
My Spanish student mentioned that he had seen -Jesus'- written this way on a poster, or something.
I have been reading up on the apostrophe in 'Cambridge Grammar of English by Ronald Carter & Michael McCarthy'. I quote:
The apostrophe 's is also added to names ending in -s. However, many writers prefer simply to add an apostrophe mark after the final -s, especially to names which have more than one syllable:
Dickens's novels -or- Dickens' novels (more common)
So, in actual fact both forms are correct.
What is your opinion, Tdol?