I'm not saccharinely religious or fanatical, just an ordinary individual with a gift for music who believes the Lord has called me to bring my songs to a wider audience. [The Priests, which O'Hagan recorded with two fellow priests from Northern Ireland, is the fastest-selling UK classical debut album, and has sold 2m copies worldwide.]
Juggling parish work with music is a challenge; some days you succeed in getting all your duties done and some you don't. I've been on photo shoots with David Bailey and performed in front of Prince Charles, but I'm a priest first and foremost, and I won't undermine that.
I've given up alcohol for Lent, but I'll never give it up entirely. I love a nice crisp Frascati, which I was introduced to in my early twenties while studying theology in Rome; that's one little part of the Italian culture I'm very much at home with.
Before the credit crunch, people didn't need God. But with the difficulties we're now experiencing, people will ask if there is some anchor or rock they can cling to.
Religion doesn't have a monopoly on the ability to inspire; raising your voice in song – whether it's at a football match or in church, gives us a great sense of uplift.
Bringing together what appears to be opposed outlooks in Christianity and Islam is one of the church's big challenges. Living in Belfast through the Troubles has taught me that an unwillingness to open one's eyes to what others believe encourages violence.
We live in a fast world and expect success in an instant. But there's nothing to beat hard graft and self-sacrifice. When I started out with music lessons in Belfast, I was taught that if I was going to be serious about music, I'd have to dedicate part of my life to it.
'The Priests' is out now on Epic