It is natural to speak of hymns as "poems," indiscriminately, for they have the same structure. But a hymn is not necessarily a poem, while a poem that can be sung as a hymn is something more than a poem. Imagination makes poems; devotion makes hymns. There can be poetry without emotion, but a hymn never. A poem may argue; a hymn must not. In short to be a hymn, what is written must express spiritual feelings and desires. The music of faith, hope and charity will be somewhere in its strain.
Hezekiah Butterworth, The Story of the Hymns and Tunes
hymns, theology