Claiming that social deficit increases religious belief is also hard without presupposing that some belief was already there. Compensating lack of social interactions by interacting with an invisible, divine, being is easier if the individual already has some prior belief. Without it, jumping to beliefs in invisible beings seems a long jump. Misattributing agency also comes a lot easier if the individual already has some idea about the agent to whom actions can be attributed.
Those of us within psychology of religion who study secularity are privileged to be working in a time where secular beliefs and nonbelievers are starting to be taken seriously within the field as a whole.