It's tricky.
The only way I think is to have a rule than can work if you are religious but is also the same for everyone else.
At work for instance, you can accommodate time for prayer by saying that people have to put the extra time back. And then you don't care if they are praying to an established faith, praying to a non recognised faith, or having a fag break. But everyone has to put the time back, including those having a fag break. Holidays - we allow people to swap if they want to, as the office is generally shut over Christmas, but there is some call for staff then. And then they get priority for other faith holidays. But then you have to make this fair with however you treat parents wanting time off in school holidays. And so on.
At school, we don't allow Muslim girls to sit in a different room from boys, but we do let all the kids pick who they sit with, unless they are disruptive, so a girl who prefers to sit with girls (most of them, Muslim or not...) can do that.
Antisocial religious requirements, such as water pistols, are like saying that your faith requires you t be homophobic. There's a basic principle that one law can never give you the right to break another law. So you are not allowed t discriminate at work on the basis of sexual orientation, whatever the teaching of your faith. Nor can you wear a visible cross in the operating theatre if you are a surgeon.