Giving thanks to Hashem for all His blessings and publicly recognizing our dependence on Him is great; in fact, it’s vital. Choosing a day to focus on that and establishing it as a national custom is nice (it sure beats choosing a day to go to the races or the football).
However, giving thanks in liberal parlance, which means refusing to mention Hashem, is heresy, and also nonsensical. It would also certainly be antithetical to the worthy intentions of those who established this holiday.
We Jews should support the former and condemn the latter.