To thank for a successful harvest belonged, at all times and in all religions, to the religious rituals of human beings.
Harvest festival recalls the unity of man and nature, which in our current western society, characterized by abundance, is fading out more and more.
Constant availability, easy procurement and often (low) prices obscure the origin of the products from field and stable and also the still hard work of the farmers.
But the celebrations are also about sharing: For many people in this world the "daily bread" is too expensive or simply not available.
So, perhaps to go into a church is not necessary to appreciate more the gifts of the earth and all people living on it and treat them with less self-evident.