Which Religions Have the Most Followers?

Joel Watts of Unsettled Christianity has posted Howard Steven Friedman’s list of the five religions that have the most adherents.

Actually, what I’d be curious about is how many followers Jesus has.  Note that this is a very different question from asking how many followers Christianity has.  Of course, no one on earth knows the answer to my question.  That answer rests with the Lord Himself (2 Timothy 2:19).