According to mine, It's Jesus'
exactly right punctuation, you never put two s' in a row, if it is only split by an apostraphy.
book - normal
books - more than one book
book's - the book owns it
if it ends with an s, then...
gas - normal
gas - more than one gas
gas' - the gas owns it
those werent very good examples, but you get my point, right?