"Dear Birthers: Stop! Sincerely, Serious Conservatives." I've held fire for the last several months as I've watched the so-called "Birther" movement gain steam. At first it was amusing, like playing a drinking game — you know, like taking a shot every time Chris Matthews explains why he insists on pronouncing the former Vice President's name "CHEE-knee." It's not amusing anymore.... But that "Birther" thing ... Seriously. Is this anything but a gift to the Democrats? ... National Review Founder William F. Buckley, Jr., Arizona Sen. Barry Goldwater, conservative historian and philosopher Russell Kirk, and American Enterprise Institute President William Baroody...