"I Origins" starts out with the idea that advocates of intelligent design point to the human eye as a challenge to Darwinism - there is no link in the evolutionary chain that could explain how sightless creatures acquired the power of vision.
So a biologist (Michael Pitt) with a fixation on the human eye (in his spare time he photographs them) sets out to find that missing link, or to create it in the lab.
He's a committed rationalist, which is ironically not rational, since he's met his wife, a deeply spiritual and other-wordly beauty (Astrid Berges-Frisbey), via a series of sequences/connections that defy reason.
At the lab, he's partnered with her polar opposite - a coolly rational scientist (Marling), who works tirelessly to find a lower-order species that can be modified to acquire the characteristics of sight.
That's as far as we should go with the plot, save to say that the whole thing eventually moves to India, land of reincarnation, where we see Pitt's character investigating the possibility that people with improbably similar eyes may share more than physical connection.
All that remains is for Cahill and company to find the perfect note of ambiguity, leaving us stranded between rational probability and spiritual possibility.
That ending eludes "I Origins," which settles instead for something that feels more like the conclusion of a conventional, more hysterical thriller.
Rare, however, is the conclusion that could satisfy both atheists and believers.
They will never see eye to eye.