Religion is a touchy issue in Beowulf, because the story is told in late medieval Anglo-Saxon Britain, which has been Christianized, but it's about early medieval Scandinavia, which is pagan. The narrator of the poem compromises by making constant references to God's decrees in general terms, but never discussing Jesus or the specific tenets of Christianity. Although the poet can't get away from the fact that his hero, Beowulf, would have been a pagan, he can suggest that Beowulf's trust in God translates easily into a Christian context. The only specific references to Christian stories are some shout-outs to the Old Testament story of Cain and Abel.
The brutal life of a medieval warrior and the blood-feuds between tribes and families that he experiences are symbolized in Beowulf by the fratricidal story of Cain and Abel.
The conflict between the Christian perspective of the narrator and the pagan activities of the characters in Beowulf results in an uncomfortable tension between theologies.