“First Reformed” follows Reverend Toller (Ethan Hawke), a former military officer who took the cloth after the death of his son in Iraq. He takes up his position at the titular First Reformed, a rinky-dink chapel with a claim to fame in is its alleged status as a stop on the Underground Railroad. When Toller is called upon by a young member of his congregation (Amanda Seyfried) to talk to her husband, Michael (Philip Ettinger), an environmental activist who recently got out of prison for nonviolent protest, the two have a discussion that leaves Toller in a state of existential crisis.