Is it true that the millennials aren’t interested in God? Or is it that they don’t believe in the God that the traditional theists believe in: the patriarchal, omnipotent, judging God who required a blood sacrifice in order to facilitate his reconciliation to the fallen human race? Well, for the record: I don’t believe in the God they don’t believe in either!
I think there is a lot of room for, and need for, a reevaluation of the theistic concept of God.
I recommend the writings of Bishop John Shelby Spong, Rabbi Rami Shapiro, Elizabeth Johnson, Marcus Borg, Elaine Pagels, Karen Armstrong,
Maybe start with Gavin Hyman, A Short History of Atheism.