The real issue is that this is a holiday that we can relate to. Just re-read Lincoln’s 1863 proclamation and I do not discern any hint of avoda zara. Tell me if you see it below. The main objection could be danger of assimilation and absorbing non-Jewish holidays. So, it is a tough piece of turkey…
ever watchful providence of Almighty God. ..No human counsel hath devised nor hath any mortal hand worked out these great things. They are the gracious gifts of the Most High God, who, while dealing with us in anger for our sins, hath nevertheless remembered mercy. … as a day of Thanksgiving and Praise to our beneficent Father who dwelleth in the Heavens. ..And I recommend to them that while offering up the ascriptions justly due to Him for such singular deliverances and blessings, they do also, with humble penitence for our national perverseness and disobedience, commend to His tender care all those who have become widows, orphans, mourners or sufferers in the lamentable civil strife in which we are unavoidably engaged, and fervently implore the interposition of the Almighty Hand to heal the wounds of the nation and to restore it as soon as may be consistent with the Divine purposes to the full enjoyment of peace, harmony, tranquillity and Union.