There is a very old saying, attributed to Voltaire, that "history is a pack of tricks played on the dead." That should be applied directly to the "rally" being held in Washington on the 47th anniversary of the most significant rally ever held in the nation's capital---the 1963 March on Washington.
The March on Washington was not about religion, although Martin Luther King was a Christian minister who used Christian religious themes to advance progressive humanist values and policies--values and policies which were and are far closer to socialism than to capitalism.
The purpose of the 1963 March on Washington was to mobilize and publicize support for comprehensive Civil Right legislation, for the most important Civil Rights legislation to be passed in the 20th century.
The purpose of this rally is to try to unite the secular and religious right of the last decades of the 20th century to attack the first African American president in U.S. history and the first President since the 1960s who was identified with progressive policies. The political themes of this march are in reality much closer to the Klu Klux Klan march on Washington in 1924 during the Coolidge administration(Coolidge made sure to leave town so as not to be seen as for or anti-Klan).
Then those hooded fascists a time when fascism had just come to power in Italy saw themselves "defending White Protestant Nordic America" from immigrants, Catholics, Jews, and of course Blacks whom they identified with crime, immorality, Communist revolution, etc.
Similarly, the "tea party" groups who have materialized as a far right pressure group in the aftermath of Obama's victory are not revolutionaries literally risking their lives to challenge the authority of the British Empire, as were those who defended British colonial power by dumping East India Company tea in Boston harbor. Rather they are what Herbert Hoover long ago called ."irreducible minority of the Republican party" those who see "Americanism" as the sum of their prejudices and property. Will Rogers also captured with they are about when he said that the Republicans were a party whose reason for existence was to reduce their members taxes.
Glenn Beck is no visionary minister and mass leader like Martin Luther King, who has risked his life over and over again to lead oppressed people against the brutal segregationist power structure in the South, as King did.
Many who watch Beck occasionally do so to laugh at him. Many see him as either a crazy or a con man or a little of both who makes his living on Fox news with hysterical rightwing tirades Many also see Sarah Palin as a sitcom character seeking fame and fortune in a political world which imitates fiction television.
It is easy to laugh at Beck , Palin and their Tea bagger friends, the way German intellectuals and large numbers of urban Germans laughed at the Nazis in the 1920s. It is easy to use reason and to refute them.
But they are not about logic and reason, but emotion, fear, and hatred. And they use the American flag and their disreputable definitions of "Americanism" to advance political agendas which can only lead to catastrophe for the American people--that is, a restoration of the Reagan-Bush policies at a time when such policies can only lead to economic and social breakdown. But we can't wait for the Obama administration, liberals and Democrats, to fight back against these forces. We must begin as a left that is a vital part of this country to do with Communists especially did in the late 1930s--to take the flag away from reactionaries and fascists by identifying ourselves and our ideas with the democratic, egalitarian values and accomplishments, from Roger Williams to Martin Luther King, that is "our America" internationalist and pluralist culturally, an America represented by its working people building cooperatively a great civilization.