In the UK bylaws are simply laws, over and above the law of the land, made by any local governing body. For example, not many years ago some local authorities in Wales allowed public houses to open on Sundays, but some didn't - they made [i]bylaws[/i] to forbid it. So, every Sunday, drinkers from "dry" areas would travel to the nearest area where the pubs were open!
So I suppose a church has a right to have byelaws. They basically say, "This is how we do things around here", and if you don't like it, tough!"
I suppose the SI Forum rules might be called bylaws. Not all forums have exactly the same rules as to what they will and won't permit.
I have no idea about church website bylaws, but suppose they are something like that.
Jeannette