Is Thanksgiving a Religious Holiday?

President George Washington made a Thanksgiving Proclamation in New York, 3 October 1789:
"Whereas it is the duty of all Nations to acknowledge the providence of Almighty God, to obey his will, to be grateful for his benefits, and humbly to implore his protection and favor--and whereas both Houses of Congress have by their joint Committee requested me `to recommend to the People of the United States a day of public thanksgiving and prayer to be observed by acknowledging with grateful hearts the many signal favors of Almighty God especially by affording them an opportunity peaceably to establish a form of government for their safety and happiness.'"

President Abraham Lincoln established the American celebration of the Thanksgiving holiday with a religious proclamation on October 3, 1863:
"To these bounties, which are so constantly enjoyed that we are prone to forget the source from which they come, others have been added, which are of so extraordinary a nature, that they cannot fail to penetrate and soften even the heart which is habitually insensible to the ever watchful providence of Almighty God.... They are the gracious gifts of the Most High God, who, while dealing with us in anger for our sins, hath nevertheless remembered mercy. It has seemed to me fit and proper that they should be solemnly, reverently and gratefully acknowledged as with one heart and one voice by the whole American People. I do therefore invite my fellow citizens in every part of the United States, and also those who are at sea and those who are sojourning in foreign lands, to set apart and observe the last Thursday of November next, as a day of Thanksgiving and Praise to our beneficent Father who dwelleth in the Heavens."
President Lincoln signed the Thanksgiving proclamation as such:
"Done at the City of Washington, this Third day of October, in the year of our Lord one thousand eight hundred and sixty-three, and of the Independence of the Unites States the Eighty-eighth."

The event that Americans commonly call the "First Thanksgiving" was celebrated to give thanks to God for guiding them safely to the New World. [Wikipedia]

The Christian group known as the Separatists (later called Pilgrims) generally shunned holidays, but periodically proclaimed a Day of Thanksgiving and Praise in response to evidence of God's favor or a Day of Humiliation and Fasting in response to God's perceived displeasure. These feast and fast days were usually held on the day of special sermons called "Lecture Day," which was Thursday in Massachusetts. [Religion Facts]
President Barack Obama doesn't invoke God's name in any variation (Lord, Father, etc...) and doesn't assign any spiritual / religious meaning to Thanksgiving in Obama's 2009 Thanksgiving Proclamation. Obama only asks us to "recall" what other presidents before him proclaimed.

Further, President Obama applies a politically correct meaning to the holiday by totally stripping the "Thanks" from Thanksgiving: "What began as a harvest celebration between European settlers and indigenous communities nearly four centuries ago has become our cherished tradition of Thanksgiving." President Obama says we owe thanks to others for enriching our lives and encourages us to share our bounties: "express appreciation to those whose lives enrich our own; and to share our bounty with others."

I agree with the sharing part -- private individuals have a responsibility to show charity and share (all year, not just the holidays). But President Obama erodes the values of America by saying we owe our thanks only to others.

Thanksgiving, more than any other American holiday (including Christmas) reminds people of all faiths to appreciate the higher spiritual authority that our Founding Fathers recognized as the source of our liberties. Without preaching a single religion, without forcing religion on others, without violating the First Amendment (freedom of religion/speech) the president should encourage people to give thanks to our Creator.

"We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness."

Happy Thanksgiving to everyone!