There are many places within Beowulf which show how culture differs. One common theme which extends throughout the epic tale is the battle between good and evil (Christian and Pagan). Seen in the battles between Beowulf and Grendel, Beowulf and Grendel's mother, and Beowulf and the dragon, the main contrast illustrated is the idea of Christian thought and Paganism.
In the opening passage of the text, the lives of Grendel and Hrothgar's people are contrasted.
Then an evil creature who dwelt in darkness, full of envy and anger, was tormented by the hall's jubilant revel day by day, as the harps resounded loud, and the song of the singer called out clearly.
Grendel, based upon the sins of his ancestors, has been exiled from the light. Sentenced to darkness, the monster despises God. Unlike Grendel, the celebrations which took place in Heorot praised God. Therefore, while Grendel despised God, Hrothgar and his people celebrated him (one example of two different cultural values).
Second, prior to the battle between Grendel and Beowulf, Beowulf states that he will wear no armor, nor carry any weapons, during his battle with the monster. Like Hrothgar's people, Beowulf is a Christian. He states that the only one who knows the victor is God.
"Let the wise God, the holy Lord, decree success on whichever side seems right to Him!”
Again, while Grendel fails to accept God's authority, Beowulf does. This shows another example of the different cultural values between Beowulf and Grendel (and evil and good).
Beowulf shows bravery by fighting Grendel, his mom, and the dragon. Bravery is an Anglo-Saxon value. When Beowulf is fighting Grendel's mother his warriors stay and wait for Beowulf to come out of the water even after a long period of time. By them staying there and wishing Beowulf would come out the water alive they showed loyalty to Beowulf.