In the mind's eye of ideological zealots, the Constitution, including the Bill of Rights, looks like one of those heavily redacted documents we see released from time to time. The Second Amendment from the Bill of Rights reads like this to them: 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. Of course many just ignore the entirety of the first half of the sentence.
Other sections of the Constitution are equally invisible to them: Article I, Section 8, Clause 15: [The Congress shall have Power . . . ] To provide for calling forth the Militia to execute the Laws of the Union, suppress Insurrections and repel Invasions; . . . Clause 16: [The Congress shall have Power . . . ] To provide for organizing, arming, and disciplining, the Militia, and for governing such Part of them as may be employed in the Service of the United States, reserving to the States respectively, the Appointment of the Officers, and the Authority of training the Militia according to the discipline prescribed by Congress.
They're blind to these sections because they can't admit that the Constitution provides for a strong central government which can enforce its laws and put down rebellion by force. That doesn't go with the "weak government" narrative. This narrative is just a convenient disguise for what has become a twisted antigovernment crusade built on a foundation of lies and half-truths.