A good poem about church is Philip Larkin's "Church Going." This poem explores the meaning of a church building in the modern era through the skeptical, yet respectful eyes of a non-religious person.
Larkin's poem begins with the speaker awkwardly entering an empty church and describing its interior. He then reveals that he often stops to investigate empty churches and begins to wonder what happens to churches if the entire population loses its religion. He imagines the churches becoming sites of mute superstition, its foundation a mere "cross of ground" tended by people who respect the church because it once "held unspilt / So long and equably what since is found / Only in separation--marriage, and birth, / And death." The poem ends with the speaker's recognition that the church is a wise place if only because of is reminder of humanity's common end: death.
Other good poems about churches include Emily Dickinson's "Some Keep the Sabbath Going to Church" and Thomas Gray's "Elegy Written in a Country Churchyard." The former poem contrasts traditional church attendance with her own "church," the beauty of nature. The latter ruminates on the dead buried in a churchyard.
Two excellent religious poems suitable for studying in church are T.S. Eliot's "Ash Wednesday" and John Donne's "Holy Sonnet 14." Eliot's poem explores a faithless person's struggle toward faith, while in Donne's poem, the speaker pleas with God to take his heart, overthrow his personal will and purify him.