It does have some christian allusions such as Cash's Mom giving him her hymn book and June and Johnnie going to church after his bad drug episode.
However, Cash's son said he wanted to emphasize his mother and father's relationship in the film, so the "God" angle is not emphasized as much as Cash's autobiography emphasizes it.
I've heard a lot of good reviews from others as well. The actors did there own singing. Maybe I'll just bite my tongue and wait for Sam's to release it half price.
I also thought the movie was excellent.
I differ from some posters here in that I thought it was quite clear about his conversion. I didn't need to see him praying...his witness to me was the change in his life.
I thought that part of the film in which he hit bottom and June told him it was time to make a new beginning (implying strongly a new beginning in the Lord) was the most poignant moment in the movie.
Vy powerful to me (having been through such an experience personally).