Not a fan of Pärt myself, but Zelenka is a good one to pair with Bach (they were contemporaries and knew each other, holding each other in high esteem).
"God" is capitalized for the same reason "Earth" or "the Universe" is capitalized. What precisely is meant may differ, but it's rich even for a materialist to argue that the name for the personification of the ground of being shouldn't be capitalized (https://en.wikipedia.org/wiki/Conceptions_of_God)