If someone is religious and does attend church regularly, they should be able to ask their employee for this time off. This might mean working later in the day (or earlier). They don’t get the whole day off unless they can show that they are not allowed to work for religious reasons the whole day. Even then, it also comes down to whether the employer can accommodate the schedule without “undue hardship.”

In Ontario and most other Canadian provinces, I would say that the prohibition against discrimination in the workplace would include the right to opt out of any prayer services. If someone is fired after raising an objection, they could then file a reprisal complaint with the human rights tribunal.