We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.
http://en.wikipedia.org/wiki/United_States_Declaration_of_Independence
The Bill of Rights just enumerates which of these rights the authors held to be unalienable.
Their interpretation of what God willed to us, then. That's fine and dandy and explains US gun law to my satisfaction.