amenity=place_of_worship but religion null entries

I made a query from planet database:

Select * 
    SELECT COUNT(osm_id) as total, religion
    FROM planet_osm_point
    WHERE amenity = 'place_of_worship' 
    GROUP BY religion
) As dummy
WHERE total > 1000

The results:


There are “53232” religion undefined entries exist.
How can I classify these place of worships, should I look “denomination” tag for that entries?

Thank you.

In one such case, I know the religion, but I don’t consider the way that I found out to be an acceptable source for OSM. On the other hand, there are references to being a temple on the building in, if I remember correctly, both Gujarati and English, and a shoe rack outside.

Hint, Hindu would be the wrong answer.

I would say that denomination without religion was mapping error, but PoW without religion just reflects a lack of information.