Many pieces of Anglo-Saxon literature reflect the influence of Christianity on the British isles. The first issue you need to consider is whether you are only treating literature written in Old English, of which there is fairly little, or literature from the period written in Latin.
Many of the extant works from England between the end of the Roman perioid and the Norman conquest were actually written in Latin, often in monasteries.
The Venerable Bede (672-735) wrote The Ecclesiastical History of the English People, one of the earliest historical works about Britain, in Latin, and was also author of a textbook on poetic composition in Latin and (possibly) vernacular verses.
Beowulf, the famous Old English epic, mentions God as the source of Beowulf's strength and judger of what is right in several places.
The Hymn of Caedmon, a seventh century monk at Whitby Abbey, is the earliest extant poem in Old English.
Many other Old English poems are re-tellings of Biblical stories or verse versions of the lives of saints. The "Dream of the Rood" is a long mystical poem about the Cross. Several shorter lyric poems and debate poems are also explicitly about Christian themes.