Too much downtime, too much gunk in the engine, and too many unanswered questions.
There are two parts of the movie. There's the tourist pre-apocalyptic phase that introuduces the characters and relationships in the movie. The best part and most undeveloped part was the Apocalyptic and more action horror oriented phase of the movie.
There are these sub plots that actually mean something like David the insane dude prophecizing about judgement day after Yam Kippur, he was interesting and I liked him. The soldiers were interesting, they were presented dilemmas and strife among the main characters. Omar the friendly tourist from the hostel was our introduction and expository tool to Jerusalem. HOWEVER all these characters just unceremoniously died without purpose by getting shot, infected, or just plain suicide.
The main characters were okay, the google glass was a "meh" gimmick of the movie but i think its best to scrap the found footage perspective and replace it with the traditional camera shot by shot method in movies. That way you'll be able to tell a story from OTHER character's perspectives rather than just ONE unlikeable, squeamish, and incompetent main character. She had ONE good selfless act in the movie which was to save the dude but everything else in the apocalypse went downhill.
The background lore and mythology elements were fascinating and needs more to be desired and then the movie just forgot about the Vatican after the intro and when David the prophet died. like BRUH.
TLDR; Cut down the tourist scenes and add more apocalypse scenes and interactions with the monsters, side characters, and mythology. It COULD HAVE POTENTIAL Dx