The Spanish have their own religious reasons for racing to the Fountain as well.
Along the way, Angelica collected a protestant missionary named Philip Swift (played by Sam Claflin). Angelica stopped her father from killing him because she was afraid his fate would be sealed if he killed a man of God. We first see Swift bound with cords on a mast, looking down upon the pirates very much like a Christ figure on the cross.
Steven D. Greydanus in the National Catholic Register noticed the oddness of Philip's character. "For once, a devout Christian character is positively depicted, if not in any depth, in a mainstream Hollywood film. What's more, the other characters generally respect his piety — even Blackbeard, whose soul (Philip) wants to save, though the missionary admits it's a long shot."
A pirate tries to convince Philip to join a mutiny by telling him he is either for them or against them. Philip responds, "I'm neither with you nor against you!" The pirate turns to Sparrow and asks him if Philip can do that. Sparrow replies, "He's religious. I think it's required."
Even Sparrow takes the clergyman as seriously as he ever gets in any of the movies, and, when he faces death, he seeks after his own redemption: "Clergyman, on the off chance that this does not go well for me … I am fully prepared to believe in whatever I must, to be welcomed into that place where all the goody-goodies want to go once they pop their clogs."
On top of the overt religious ideas are the underlying religious themes in the movie. There is conflict on multiple levels:
Protestant versus Catholic.
Religious versus magic.
Theology versus myth.
Eternal life promised by God versus eternal life promised by the Fountain.
Although there are many reviewers who saw no point of having the missionary character in the movie (one blogger called Philip the "random religious dude"), his character embodies the religious side of the equation.
On the other side is a fish.
The mermaid and the missionary
To make the Fountain work, you need a mermaid's tear. In this movie the mermaids are less Disney's Ariel and more out of The Odyssey. They are vampire-like man-eaters. But, as "Twilight" showed, vampires have feelings too. Blackbeard captures a mermaid (played by Astrid Berges-Frisbey) and Philip shows compassion to her and gives her a name: Syrena. His love and self-sacrifice saves her and her love in return saves him.
So here you have in one corner a religious missionary. In the other corner a magical mermaid. And they fall in love and save each other: redemption?
By contrast, the Spanish came to the Fountain to destroy it as a blasphemous affront to real eternal life. Religion attacks mythology. The Spanish break everything in the place and shoot a few British as well. But, the fountain still works anyway.
Angelica is mortally wounded as is her father, Blackbeard. She tries to use the magic of the fountain to save her father's eternal soul. It doesn't work. She ends up saving herself instead.
When people look at religion in films, D'arc says they should be aware of the inherent problems of communicating faith in films. "When you are dealing with religious sentiment and with faith, that's a very tough thing to have in a two-dimensional picture on a screen, because faith embodies thoughts and emotions that are in someone's heart. Well, how do you picture it so that the emotion and feelings are conveyed the same way to the diverse audience that is viewing this? That is the Gordian knot that filmmakers have been trying to cut, and very few have been able to do that."