This could have a lot to do with its wider appeal. Wider because church symbolism means a lot to people, and those who appreciate it don't necessarily have the same strong feelings for nature symbolism.
Originally Posted by Diapositivo
Church for me, as I was influenced by a Boy Scout upbringing, means rocks and lakes, rivers and trees. For my wife, influenced by a Mission San Carlos Borromeo upbringing, crosses and saints, Jesus and Mary mean more.
In my own home I have only a few prints on display. Two nature shots, two shots of my kids, and five shots taken in and around missions.
I don't even "get it" in my own work, why shots that include religious symbolism are more popular with my chosen audience. I much prefer the nature shots I have taken, they move me directly and personally.