What type of music composition is "Amazing Grace"?

"Amazing Grace" is a Christian hymn published in 1779, written in 1772 by English Anglican clergyman and poet John Newton (1725–1807). It is possibly the most sung and most recorded hymn in the world, and especially popular in the United States, where it is used for both religious and secular purposes. It has been associated with more than 20 melodies. In 1835, American composer William Walker set it to the tune known as "New Britain" in a shape note format; this is the version most frequently sung today.

Source: Wikipedia