How about you just scrap the town entirely and just have a few survivors? That way, being on the town isn't a free "You win!". Some of the scum teams should have 1-shot kills while others should have recruiting powers. Other possibilites include a 2p team with a doctor, 2 RBs, an unlynchable (but very killable) guy, an unkillable (but very lynchable) guy, ect.
That would work too, the intent was to create a group that was "undecided", and large enough for the religions to consider it worth influencing. I'm not sure how survivors are different from the town in that context. I'd also worry about town/survivors lynching randomly Because They Can, so another possibility would be to hand out pro or anti religious roles to the townies (sort of like lynchers and anti-lynchers, but targeting religions).
Toony: The idea here would be that most of the players would be broken up into small groups with one-shot nightkills, rather than the mass slaughter that would happen if they were all "full" mafia groups.
Stealing a bit from Servant Corps, you could also have a leader from each of the religions and mostly townies, with the leaders recruiting townies into the different religions. I'd say that trying to recruit an already-recruited person would result in failure but not death, though recruiting another leader might. To mix things up a bit, there could be some "survivors" who would remain recruitable after conversion, or an array of powers that a leader could transfer to already-converted people (spend a night action to transfer the ability to convert, for example). I'd also make night-kills fairly rare, to let the game go on a bit longer. Something like:
The Jewish leader (Moses for flavor) starts off with the ability to convert, transfer abilities, roleblock, and grant double votes for the next day.
Night 1, Moses converts townie A
Night 2, Moses transfers the ability to convert from himself to townie A. Moses can no longer convert, but Townie A can. Night 3, Townie A can convert Townie B while Moses roleblocks the person he suspects of being the leader of the Hindus.
The idea would be that as religions grew, they would effectively gain more actions per night, and spread the risk of losing their leader over more people. Of course, if Townie A was a survivor and was converted Night 3 by the Hindus, that would be bad for them. Similarly, losing a fresh convert to a lynch isn't that big a deal, but losing the person you just transferred the ability to convert to would be.
For that sort of thing, I think I'd want a leader for every 4-5 townies or so, to let the game develop reasonably.