Religion and the law

[robvalue]

Let's assume we're in a secular country (in theory or in practice). Feel free to comment on how answers would vary across different countries. We have interactions between religion and the law, and I'm concerned here about how this works on a personal level.

1) Informally, what constitutes a religious belief? How is it any different from a regular belief? What elements must it have, other than calling it a religious belief?

2) Legally, what constitutes a religious belief?

3) Are there situations in which I would be legally allowed to perform some sort of action/ritual because of a religious belief, where I wouldn't be allowed to do something similar just because I feel like it? If so, is that justified? If not, what's the point of the law?