In general, I try to put any non-obvious sources in the source tag of the changeset, so users can determine exactly where the data comes from. You can add multiple sources as well.

Regarding the licensing, the general consensus in the OSM community is to err on the side of caution regarding datasets like this, since they took some effort to gather (often called "Sweat of the Brow"). Factual data scraped/gathered from individual church websites is completely acceptable though. 

https://osmfoundation.org/wiki/Licensing_Working_Group/Minutes/2023-08-14#Ticket#2023081110000064_%E2%80%94_First_party_websites_as_sources

My personal recommendation (not a lawyer, just another contributor) is to try to get explicit permission from the website to use their data.