[quote name='Strell']Wrong.
Jesus' is correct because generally well-known names are "allowed" (this is the best way I know how to describe it) to have only the apostrophe. There are other examples, but I don't know any off the top of my head.
In most cases, however, names ending with an s MUST use both the apostrophe and the s. So it's Mr. Jones's dog, or Tess's lemonade, etc. And yes, you are supposed to pronounce (written here somewhat phonetically) it as, "Mr. Jones-ez dog."
An apostrophe only is used when it's plural. The ducks' pond.
Generally no one is going to notice no matter what, since grammatical rules tend to be forgotten or warped as people get older. A better thing to do is just eliminate the need for it completely by changing the wording of the sentence. "The hat Mr. Jones has."
Mr. Jones' dog, if you look at it purely grammatically, implies something....really strange, actually. It's almost as if it is saying there are many people named Mr. Jone, and that you are talking about them collectively as either all owning a dog or all having dogs individually. There might even be some obscure rule that said you could get around this with "Misters Jone," implying several people, but even that is sort of in a gray area.
Point being it all gets muddy.[/quote]
http://www.grammarbook.com/punctuation/apostro.asp
Use the apostrophe to show possession. Place the apostrophe before the s to show singular possession. NOTE: Although names ending in s or an s sound are not required to have the second s added in possessive form, it is preferred.
I certainly agree with things getting muddy. The problem I find is that people start using made-up words and made-up grammar rules and they eventually find themselves into grammar books and dictionaries. This may be one of those cases, but I know I learned this rule back in grade school (so more than 20 years ago).