Margaret Wente, Math and Christianity: More factual/attribution errors?

Wente writes that Christianity is the “fastest-growing religion in the world today”. “By 2050, Christians will outnumber Muslims 3 to 1.”

She claims that this comes from a “new report on global Christianity from the Pew Research Center.”

A pdf of the report is here, and if anyone can find anything suggesting that “By 2050, Christians will outnumber Muslims 3 to 1”, please advise. My search turns up no 2050 projections at all, and Muslims are not mentioned except in a footnote on Russia.

Wente goes on to describe a 2002 book by Philip Jenkins, offering similar points and the identical selected quote found in this book review:

There, another Jenkins quote appears: “Soon the phrase “a White Christian” may sound like a curious oxymoron…By 2050, there should be about three Christians for every two Muslims worldwide”.

The “should be” looks like it’s followed by a proviso – confirmed when Jenkins notes that while the percentage of Christians worldwide has remained the same for the past 100 years, Muslim numbers have surged from 12 or 13 percent in 1900 to just under 25 percent today.

Unlike the Pew Report, Jenkins does offer 2050 projections, writing: “Christians in 1900 outnumbered Muslims by 2.8 to 1. Today the figure is 1.5 to 1, and by 2050 it should be 1.3 to 1.” (Philip Jenkins, “The Next Christendom”, page 203)

Last month, Wente picked up an unsuspecting "John" and erroneously turned him into the “face” of the Occupy movement. She’s also been known to turn scientists into fishermen. These mishaps usually occur through a failure to attribute, which is a fairly common occurence. Here she attributes statistics to a report, but the claims don’t seem to be there. Did she make up a billion extra Christians, or subtract a few million Muslims? Did she accidentally turn Jenkin’s 2050 ratio of “1.3 to 1” into “3 to 1”? And why did she claim that these figures come from the Pew Center?