Today America marks the 18th anniversary of 9/11 with solemn ceremonies. As one people we said we would never forget that day. Nearly 3,000 lives were lost amid the smoldering ruins of the Twin Towers, at the Pentagon and on a grassy knoll in Shanksville, Pennsylvania. Our first responders showed incredible bravery. American flags were flying everywhere. Young and old left their jobs to enlist in the military. But remembering 9/11 is more than a once-a-year ceremony. It’s about taking to heart the lesson we should have learned that day—Islam’s goal is to destroy America and the values embodied in our Declaration of Independence and the Bill of Rights. Because many Americans have forgotten that lesson, Islam’s plan for civilization jihad is working. Islam is defeating us from within, without firing a shot. Instead of tolerating this evil ideology, we should heed the words of Abraham Lincoln in his 1838.