This sounds like a subplot from a Tim LaHaye/Jerry Jenkins novel.
With a little Dan Brown thrown in for oggie-boogie effect.
Really? I don't recall the world religious figure who sided with the antichrist in the "Left Behind" series being portrayed as the Pope -- or even Catholic, for that matter. IIRC, the robed poseur appointed to head the antichrist's lapdog global religious ecumenical .org was some other pubah randomly elevated to the post. Pls, correct me if my memory doesn't serve me well at this point.