It's not been in doubt, it's pointing out the factual nature that any social grouping, religious grouping, racial grouping that results in people actually coming together in a group results in a higher probability of contagion.Of course. When has that ever been in doubt?
If the pastafarian religion emphasized celebrating the spaghetti monster could only be done where pasta consumption was conducted 1.5m apart and no ceremony was valid if more than 10 people gathered, it would be much less likely for any spread.
Which leads to the observation that the data tells you some religious groups (and in Israel and New York, Hasidic Jews are one such community affected severely [1]) processes are going to end up with more of them contracting COVID19 than others.
[1] ‘Plague on a Biblical Scale’: Hasidic Families Hit Hard by Virus
I do appreciate that most people are trying pretty hard to keep to the principles of differing between correlation and causation and avoid heading down the slippery slope to racism and discrimination.