Corita’s early work was heavily influenced by byzantine religious art work. In 1952, she won several prizes for this screen print. Corita is already printing color over color, shape over shape, in part because she decided she didn’t like what was originally printed on this poster and decided to print over it.
My impression is that Corita was essentially populist, which can be seen in her interactions with students, the community, and choice of mediums. Silk screening, or serigraph, was inexpensive, and is still considered a populist art form as its common for t-shirts and protest signs.