Kiwi's Kooky Kake Kafé
Because my religious beliefs don't support divorce, I should have the freedom to exclude these people or anyone else I wish from my shop/refuse to serve them.
No, to this example, or any other grounds for discrimination between customers. Your shop doesn't exist in a vacuum. It's a part of the market-place you enter, where you can freely buy safe ingredients at honest weights and have people browse your wares without the constant threat of looters from the next village just grabbing what they want off the shelves.
You get the benefits of food safety regulations and inspections that stop your competitors from undercutting you on price by not hiring someone to wash their cake pans or treat their rat infestation (Because you wouldn't want to mistreat your customers, naturally). You get the efficiencies from trust when customers, knowing your ingredients are not tainted, your kitchen is clean and they won't get mugged outside your shop door, will buy your cakes with confidence, even if they don't know you.
That marketplace is the gift of your fellow citizens and taxpayers via the government. They don't get to discriminate based on your beliefs, neither should you. This is a basic quid-pro-quo and the government has a compelling interest in non-discrimination in marketplaces. For both customers and employees.
You can hire people to work in your shop, and there are candidates available with the education and skills you need. They're willing to provide labour because they know labour laws ensure they get paid and there is some protection* against mistreatment.
*subject to country. NZ standards should be pretty up there.