Thanks to Terrifel from the Straight Dope message boards:
1956 was of course the worst year that the United States had ever faced. Wracked by turmoil and social upheaval, beset by enemies within and without, the nation thrashed about like a dying, constipated beast. Whole cities crumbled into ruin amid the chaos as American society teetered on the very brink of collapse. The horror of that time has made the name of Eisenhower synonymous with anarchy even to this day. My father would never talk about how he and his family survived those grim times.
Fortunately, in the very nick of time, legislators realized the true cause of the crisis: America's national motto wasn't stupid enough. Like all of the country's other woes, this disaster could ultimately be traced back to that most sinister of Americans, Thomas Jefferson. The same treacherous impulses that led him to betray his rightful King also inevitably prompted him to sabotage the fledgling nation by giving it the worst possible state motto: E pluribus unum. Not only was this an unforgivably pompous classical reference, its subversive message-- "out of many, one--" would result in a catastrophic tradition of escalating tolerance and unity that was doomed to tear the country apart in less than two hundred years.
I think it is time to change the motto from "In God We Trust" to "Try And Stop Us". Or perhaps "Are You Looking At Me?".