Definition of chaplain : 1: a clergyman in charge of a chapel 2: a clergyman officially attached to a branch of the military, to an institution, or to a family or court 3: a person chosen to conduct religious exercises (as at a meeting of a club or society) 4: a clergyman appointed to assist a bishop (as at a liturgical function) https://www.merriam-webster.com/dictionary/chaplain
Seems to me that someone who claims there is no God, fails to meet any of those criteria. Not blaming them, but the institution, Harvard, which founded in 1636 in anticipation of the need for training clergy (Christian) for the new commonwealth, has forgotten its roots.

Harvard University has selected a man who does not believe in God to be the school’s chief chaplain.
Chief Chaplain Greg Epstein is the author of “Good Without God: What a Billion Nonreligious People Do Believe.” He also serves as Harvard’s humanist chaplain, the Massachusetts Institute of Technology’s humanist chaplain, and as convener for ethical life at the Massachusetts Institute of Technology’s Office of Religious, Spiritual, and Ethical Life…