President Biden brought some fire this week. If he can keep it stoked, it might ease concern about his octogenarian vigor and boost his sagging approval ratings. After Hamas terrorists attacked Israel and killed more than 1,000 civilians, Biden delivered what may have been the most powerful speech of his presidency. In a forceful 10-minute address on Oct. 10, Biden condemned the Hamas attacks as “sickening” and “abhorrent,” while warning other Israeli foes against getting involved and making America’s position crystal clear: “The United States has Israel’s back.” It was a refreshing demonstration of resolve and moral clarity that even…