We've never cruised with HAL so have never attend a religious service on their ships, but we have attended Christian worship service on Princess and Celebrity. The service on Princess was several years ago, so probably not relevant except for the fact that its arrangement was exactly the same as our more recent experience on Celebrity this past November. In both cases, a pastor on board as a guest arranged for the use of a meeting room for Sunday service. Also, in both cases, we learned of it by word of mouth because it wasn't in the daily planner or on the app. On our most recent cruise, with Celebrity, the service was posted on the LED events display next to the Guest Services desk.
I'm surprised and sorry to hear that your experience with Celebrity was that of resistance. A meeting room for regular Sunday service was arranged for both Sundays we were onboard. Not only did we have the use of a meeting room and a listing on the LED events board, but when my husband approached the pastor about providing audio-visual assistance for the following Sunday, Celebrity gave us permission to use the equipment (screen, projector) in the room. Also, since no one had booked the adjoining room, and it was apparent that the second service was going to draw a bigger crowd, they opened up the partition for us and set up more chairs. Further more, the Jewish people on board also had services with a Kiddush. At least on this ship and on this sailing, Celebrity was hospitable and accommodating.