Last year on Flag Day (June 14) many secular Americans posted an interesting video on their Facebook profiles and elsewhere. The video, a 1939 clip of Porky Pig reciting the Pledge of Allegiance, is a great educational tool, because he recites the Pledge in its original version without any "under God" wording. See the Youtube video here:
Many Americans are unaware of the history of the Pledge. It was written in the 1890s, but the "under God" wording wasn't added until 1954 at the height of the McCarthy era, hardly a proud chapter of American history, after heavy lobbying by religious groups. Thus, the original (God-free) Pledge was used during the First World War, the Great Depression, and the Second World War.
Ironically, politicians and religious conservatives made a mockery of the wording "one nation indivisible" by adding the reference to God. With the religious wording patriotism was suddenly synonymous with religiosity, so secular citizens were marginalized and the nation was quite divisible.
Secular Americans, of course, have fought and died for their country, they pay taxes like everyone else, and they otherwise contribute to the greater good. To show solidarity with them, consider posting the video, a great history lesson indeed, for Flag Day.