It is thus somewhat misleading to concentrate your photographic efforts on covered women and people praying. A non-obvious and not-too-easy-to-find one is Rustem Pasa, up some stairs from a busy nest of market alleys. [Visiting Christian sites elsewhere in Turkey can be interesting even though most of the remaining Christians departed in the 1950s. One Istanbul synagogue, Neve Shalom, has been attacked three times: September 6, 1986 (by Palestinians), March 1, 1992 (Palestinians again), and November 15, 2003 (by Turkish members of Al-Qaeda).
Istanbul is a sprawling collection of villages, all of which have exploded into each other, rather than one coherent city.
Unless you have months on the ground, you will have to pick one or two Istanbuls and leave the rest for a future trip.
Why not start in the Bazaar, the world's oldest shopping mall?
It is right in Sultanahmet, probably walking distance from your hotel.
For the tourist, the practical effect of this change is that photographing religion in Istanbul means photographing Islam.