Vincent de Phily
It's probably not used regularly/frequently, but it apparently hosts a mass every now and then: https://www.youtube.com/watch?v=B202QBh1-Lk

I've hiked past places in Ireland obviously serving as place_of_worship regularly despite being little more than a cairn and a small alcove, so seeing a mass on Skellig Micheal doesn't surprise me.

I suggest putting amenity=place_of_worship back.