Newton was an anti-Trinitarian who would have been a heretic by the standards of every church of his day, and he spent as much time on alchemy as physics. Isn’t “devout Christian” doing a lot of work?

Newton was heterodox on the Trinity, and devout theist who wrote extensively on Scripture is the more accurate description. The alchemy is beside the point. The claim needs only that Newton saw his science as the study of God’s ordered creation, which his letters to Richard Bentley confirm, not that he was orthodox. A heretic who did physics to trace the hand of God is still a counterexample to the warfare story.