The phrase you quote does not stand alone. It is separated by a comma into two phrases. I failed to point out above that "the right of the people to bear Arms" is itself a subordinate clause, making the Militia the thing that "shall not be infringed." Now we have the question: Why on God's green Earth would the government want to infringe a Militia? The only possible answer is that the Militia is not a government agency, but the people themselves, whose "right to bear Arms" establishes and maintains that Militia without government permission or interference.