The Washington Post had a long editorial today warning us against "overreacting" to this one incident. After all, as they note, there are plenty of other refugees who haven't killed anyone yet.
Bottom line, admitting muslim refugees from these backward countries does nothing to help our country and exposes innocent people to deadly risk. As we have seen, often it is not even the actual refugees who are problems but their children, years or decades later.
Saudi Arabia funded ISIS and al Qaeda. We now know they were somehow involved in 9/11. To date, they have taken in zero refugees. When they let in a million or so, get back to me about our obligation.