"Surely the point is, that no one has to prove their spiritual beliefs?
If I choose to believe in a supreme being, the tooth fairy,the natural life force, or Santa clause, what has it to do with you?"

Yep! You are free to believe anything you like and if you keep your silly notions to yourself you're not required to prove anything.

But if you want other people to respect your 'beliefs' and to afford them special status within society THEN you have to offer some proof.

And if you insist on 'evangelising' and requiring other people in society to live by your beliefs and seek to influence the political process such that other people in society have no choice but to live by your beliefs THEN you have to offer some proof ... but first you can f**k off!!