If he were Muslim, we might expect to hear reports of his praying five times a day, or fasting during Ramadan, and we would probably not see him attend a Christian church or profess to be a Christian. I think these latter two are probably not part of Islamic doctrine.
The moslem religion allows for lying, which would certainly include going to any non-moslem church (or pastoring any church while attaching any label to it), in order to perpetrate itself.
Praying five times a day would be kept as secret as the truth of his religion, in such a scenario. And as a moslem infiltrator, his agenda (like that of a bin Laden or an Achmadinejad) would be much more weighted towards stealing and maintaining power for himself than towards any kind of spiritual purity.