Gratitude is an existential orientation. It is a posture of being in the world. To be in a state of gratitude is to be in response to something or someone who has bestowed some object or performed some action that puts one on the receiving end of a relationship. It therefore presupposes and implies the existence of a relationship, a relationship that is definitive of one's being; it sets the tone of that relationship as being colored by loving kindness and gentle caring; and it presents a set of guidelines for how to behave.
Gratitude is a response to some primary act of beneficence. It is not clear how one can orient oneself into a posture of gratitude without having some providential god on the other side of the relationship.