“A Mighty Fortress Is Our God” is an example of-

A religious song or poem of praise to God is called a hymn. Usually it is sung by chorus to express religious emotion. Spenser’s “Fowre Hymnes”, Martin Luther’s “A Mighty Fortress Is Our God” and Shelly’s “Hymn of Apollo” are some of the well known hymns in English.
Source: An ABC of English Literature - Dr M Mofizar Rahman