A religious song or poem in praise of God is a hymn.
A writer of hymns is a hymnist.
A collections of hymns is a hymnal or a hymnary, which may or may not include music.
The music to which a hymn may be sung is a hymn tune.
The singing of hymns is hymnody.
A student of hymnody is a hymnologist.
And, finally the scholarly study of hymns, hymnists, and hymnody is hymnology.
Dr. Jeannine Jordan, church musician and hymnologist, is also the creator and performer of the organ and multi-media concert experiences, Bach and Sons and From Sea to Shining Sea, as a concert organist.