There is virtually no record of the earliest music of the Christian church except a few New Testament fragments of what are probably hymns. Some of these fragments are still sung as hymns today in the Orthodox Church, including "Awake, awake O sleeper" on the occasion of someone's baptism.
Being Jewish, Jesus and his disciples would most likely have sung the psalms from memory. However, without a centralised music industry, the repertoire of ordinary people was much greater than it is today, so they probably knew other songs too. Early Christians continued to sing the psalms much as they were sung in the synagogues in the first century.
Aside from hymns taken from the Bible itself, the earliest hymn still in use today is probably O Gladsome Light (Greek, Phôs Hilaron). In the fourth century, Basil the Great referred to it as already being a rather old hymn.
Some of the popularity of Arianism in the fourth century can be attributed to the catchy songs that the priest Arius composed in its support. The popularity of the songs helped increase the popularity of his teachings. Ephrem the Syrian composed a number of hymns later in the fourth century that supported what eventually came to be recognised as more orthodox doctrines.
Troparia and Kontakia are two early forms of hymns that became incorporated into the Church's worship.
At the conclusion of the Fifth Ecumenical Council, Emperor Justinian I is reputed to have composed a hymn summarising the council's conclusion, Only begotten Son. That hymn was since incorporated into the Divine Liturgy of John Chrysostom and is still widely sung today.
The tradition of Christian hymns in the English language is closely tied to Protestantism. Protestant hymns can range from the Reformation organ pieces of J. S. Bach to the American folk hymns found in The Sacred Harp. Martin Luther composed a number of hymns in the 16th century, reportedly borrowing some of their melodies from popular tavern drinking songs of that period.
Another famous hymn composer is Charles Wesley, brother of John Wesley. Some hymns, particularly Christmas carols, are widely embraced by various denominations while many hymns are restricted to certain religious traditions. In some cases this is due to doctrinal differences reflected in the words of the song but in many cases it is the result of tradition and the use of denominationally-produced or -approved hymnals.
The use of hymns was a factor in several historic schisms among Protestant denominations with more traditional members insisting on the use of only the psalms in the service.