From Lawyers, Guns and Money:

The government will run out of money on December 11. Unless additional funding is approved before that date, the government will shut down.

The House Freedom Caucus wants the next speaker to commit to not funding the government at all unless President Obama (and Senate Democrats) agree to defund Obamacare, Planned Parenthood and a host of other priorities. This is essentially the Ted Cruz strategy which prompted at 16-day shutdown in 2013. This would now be enshrined as the official policy of the Speaker Of The House.

The House Freedom Caucus wants the next speaker to commit to oppose any “omnibus” bill that would keep the government running. Rather, funding for each aspect of government could only be approved by separate bills. This would allow the Republicans to attempt to finance certain favored aspects of government (the military), while shuttering ones they view as largely unnecessary (education, health).

This is what you get when you figure out how to game the flaws in the Constitution. They are determined to break the country.