From The Scylding Cycle: Overview by The Ark:
... Though the first half of Hrolfr Saga is entirely Pagan, Christian themes begin to appear when Bodvar enters the plot. Near the end of the saga, Hrolfr refuses gifts of arms presented by a disguised Odin, and Bodvar warns that this error will cost him his life. The author, however, contrary to the clear intent of the original narrative, asserts that it was the heroes’ lack of faith in Christ which cost them victory and the final pages of the saga are filled with awkward, moralizing interjections which lament the heroes’ lack of Christianity. Both due to its setting and its partial Christianity, this saga introduces us to the world of Beowulf, creating a seamless bridge between the Pagan Norse material and Christianized Old English poem.
BEOWULF
Beowulf is the longest surviving work in Old English and the only work in this section not in Old Norse. It is an epic, composed in alliterative verse and preserved only in a single manuscript copied around 1000 AD. The date of the poem’s composition is debated, but it may have been as early as the 700s. The story itself is clearly quite old, likely older than the composition of the poem in its present form, as is standard for oral tradition. The epic was composed in West Saxon Old English, but with archaisms which suggest transmission from an earlier tradition. Though the poem is in Old English, it is set in Scandinavia, with the Geatish (of southern Sweden) hero Beowulf coming to the aid of the Danish royal court featured in Hrolfr Kraki Saga.
While the Christianity of Hrolfr Kraki Saga is awkwardly and intrusively inserted into the narrative by the author, Beowulf’s Christianity is both more subtle and more complete. The monster Grendel is said to be a descendant of Cain and God is invoked throughout the poem. Yet strangely, there are no mentions of Jesus Christ and most Biblical references refer to the Old Testament. Metaphysically and morally, the poem appears to be almost entirely Pagan, with fate, honor, kinship, hospitality, and heroism saturating the text and driving its plot. It is possible that a version of the poem was in circulation before the Christianization of the North and it is almost certain that the story itself predates the coming of Christianity.
One of the most interesting aspects of the epic is its many references to other Germanic legends and figures, such as Eormenric (the same Jormonrek who kills Gudrun’s sons in the Volsunga Saga) and Wayland/Volund of the Poetic Edda. For us, the most interesting of these is when a bard references Sigmund, a “Waelsing,” and his nephew, Fitela, who is presumably Sinfjotli. Many other references are embedded within the poem, with the most notable being a partial telling of the Finnsburg legend, preserved separately in the short Finnsburg Fragment. The poem, therefore, is saturated with Germanic legend, brought to England by the Anglo-Saxons and later by the Danes and Norse during the Viking Age. In fact, some scholars, amoung them Tolkien, theorize that the Hengest of the Finnsburg legend is the same figure as Hengist, the brother of Horse, who is said by Bede to have led the Angles, Saxons, and Jutes in invading England alongside his brother.
When Caesar led the first Roman invasion of Britain during his Gallic Wars in 55 BC, the British Isles were inhabited by various insular Celtic peoples all speaking Celtic languages and practicing Celtic Paganism. ... In 410 AD, the same year that Alaric and his Visigoths sacked Rome, Emperor Honorius sent word to Britannia to tell them that they would no longer receive Rome’s support. Not long after, the Angles, Saxons, and Jutes, coming out of Denmark and Northern Germany, began to settle England. Roman-British Christian culture was replaced by Germanic culture, religion, and language. Soon after, Anglo-Saxon England was converted by missionary work both from the mainland and Northern Britain, where Christianity had persisted. But beginning in 793 AD with the Viking raid on Lindisfarne, the Norse would raid, invade, and settle England, bringing a new wave of Germanic Pagan influence to the Island. England continued to exchange hands between Norse—mostly Danish—and English rulers until it was conquered by the Normans in 1066. As a Christianized Old English story set in late Migration Period Scandinavia, Beowulf perfectly reflects England’s complicated history.
Though Beowulf is woven from Pagan cloth, some scholars read it as a highly Christianized poem, some even likening Beowulf to Christ. I find such analyses unconvincing. If the poem’s narrative anywhere displays Christian influence, it is in its end which seems to partly criticize the Pagan heroic ethos and partly lament its collapse.