Sean, I was in Vienna this past summer and went to Karlskirche where Beethoven's Requiem Mass was said, if that tells you anything. Incidentally, this was where Schubert's was as well.
I think LVB was Catholic, but was influenced by the humanism that was so rampant at that time, as so many were. My family went to visit his grave at the Zentralfriedhof and prayed for him.
You can hear the struggles he experienced in his music, as well as the beauty and depth that he was blessed with. I am grateful for his music.