Although I don't have any references for works of this type, it seems to me there are a couple of ways to approach doing it. As with many subjects, the first key is probably "understanding" the faith and how it and the associated symbology manifests in its believers. Then, once you know what to look for, the photography can be approached from either a photojournalistic perspective (the luck of being in the right place at the right time, with the right measure of sensitivity), or a "staged" photojournalistic manner (creating the right time, right place, but still having the sensitivity - something akin to editorial work). While "it" is all in your heart, you can use your mind to create the scene that conveys the message.