Lennon subsumes all religion and all religious experience without distinction under that catchall concept he labels God, and blurs sacred texts, practices and beliefs with human celebrity and the accolades afforded to them, whether rock stars (Elvis, Zimmerman [= Dylan], Beatles) or politicians (Hitler, Kennedy). This may explain why U2, rather unexpectedly, does not use the term "God" at all in their song, apart from the title. Bono refuses to group all religion together or mingle sacred language with reverence for renowned individuals. U2's God song offers instead a far more nuanced understanding of the Divine, which includes a theological particularity absent from Lennon's lyrics.
God, parts 1, 2, and 3
Michael Gilmour, who published an article some time ago about U2 and Jeremiah, has an interesting post up at HuffPo comparing U2's 1988 response to John Lennon's "God" to Larry Norman's 1993 response. This is a cool topic to explore. Excerpt: