I've seen a lot of live videos of this song from their previous concerts. Then I understood. There are like one or five concerts where she often times put her hand up and her finger points up. There was also a part of the song in the concert that isn't in the album where they started singing all the oh's still pointing up. Then it was quite obvious that her heart. Is for god. It's not a typical girl luvs boy (though that may also apply) but the real reason why they composed that was because it's for god surrendering herself.
If you don't believe me then see for yourself. At the send of the song I had really deadly goosebumps, understanding it all. =">