The film is Martin Scorsese's period drama Silence, about Jesuit priests facing persecution in 17th century Japan. And Garfield says that being part of the film is still reverberating.

"My sensitivity, I think, gets me in so much trouble," he says. "It gives me a tremendous amount of wonderful things in my life, as well. It means that I can connect deeply to things, whether it's other people, characters I play, the struggles of others. But in the same breath, it means I can just as easily connect to the stuff that really f**ks with me! I'm very permeable in that way."

Andrew Garfield grew his hair for SilenceAndrew Garfield in Silence

To prepare for the role, Garfield worked with Father James Martin, who led him through a series of spiritual exercises. "I was so excited to work with Marty [Scorsese] that I said no to everything else," he laughs. "I thought if he's been wanting to make this for 28 years, the least I can do is give one year of my life to getting ready. It was my pleasure doing all of that preparation."

The process included a seven-day silent retreat during which he never said a word. "It was pretty amazing," Garfield says. "A lot of the film is my character Rodrigues in prayer with a seemingly, supposedly silent God. Those seven days really enhanced my ability to convince myself that I wasn't bulls**tting. When you meditate or pray, the idea is you enter a sacred space where you can commune with the divine or whatever you want to call it."

More: Martin Scorsese talks about religion in his movies

And Garfield enjoys how the film lets the audience grapple with issues without telling them what to think. "People who are certain are terrifying to me," he says. "That's how religious wars get started! The beauty of this film is that everybody is having such distinct experiences. There's nothing manipulative about it. It faces people with themselves, and so their responses are very revealing, whether they are deeply moved by it or deeply offended by it or bored by it or inspired by it."

But the most difficult aspect of the film for Garfield and his costar Adam Driver was losing weight to play tortured prisoners. "It was a running joke between me and Adam and a few people and Marty," Garfield laughs. "It was like, 'When do I get to apostatise? Because I'm ready to eat!' Food was everything. That was the most overriding sense of all things. It was like, 'Give me the burger!'"

Watch the trailer for Silence: