The Constitution is open to interpretation. It has even been called a "living, breathing document" by some.
The Constitution was ratified 1788. The first 10 amendments (Including your precious Second) wasn't ratified until 1791.
The Eighteenth Amendment was ratified in 1919. In 1933, we decided the Eighteenth Amendment was a mistake and repealed it with the ratification of the Twenty-first Amendment.
As for the Second Amendment, it has been the subject of much debate. Let's take a look at it.
This ambiguous wording as been interpreted two ways. One, is that the right to keep and bear arms is only held by people in well regulated militias (state run militias). The other is that the right is to keep and bear arms is separate from the militia part.A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.
It wasn't until 2008 in District of Columbia v. Heller that it was finally decided that the "well regulated militia" part meant "nothing more than the imposition of proper discipline and training" and not any type of military service.
This interpretation can still be changed by future rulings of the Supreme Court. So your "God given right" wasn't even the "right" you thought it was until 2008.