Before Beowulf and the Geats arrive to help Hrothgar, we are told that Heorot, Hrothgar's magnificent guest-hall, has been rendered completely useless by Grendel's attacks:
So Grendel prevailed and fought against right,/ one against all, until empty stood/the best of houses. That time was long; twelve winters' length the torment endured. . . .
During this period, Hrothgar's warriors have repeatedly tried to defend Heorot but to no avail. Grendel has conquered the best of Hrothgar's warriors, and by the time Beowulf and his men arrive, Heorot has in effect become Grendel's because there are not enough of Hrothgar's men to defend the hall.
We learn that Hrothgar and his council turned to their pagan gods for assistance:
Sometimes at altars they made offerings/to pagan idols, and prayed aloud/for the spirit-slayer to send them help/for the people's distress. . . . they didn't know the Maker/, the Judge of Deeds, they didn't believe in Captain God. . . .(ll.176-181)
This is an important passage in Beowulf because it establishes that Hrothgar and his court are powerless to stop Grendel and, more important, it establishes the fact that, unlike Beowulf and the Geats who are Christian, Hrothgar and his people are pagan. The poet is reminding his listeners that Hrothgar and his council are praying for help to gods who cannot help them--"so Halfdane's son [Hrothgar] seethed at his troubles/in endless anger."
The pull of two religions--pagan and Christian--is clear throughout the poem. At the time of the poem's composition, sometime before the ninth century, Scandinavian people were in the process of switching their allegiance from paganism to Christianity. At many points in the poem, however, we find references to God and Christ, as well as references to fate, a holdover from paganism. The poet, however, who understood that paganism was losing its battle with Christianity as the dominant religion, is reminding his listeners that, by praying to pagan gods, Hrothgar's prayers are not going to be answered--at least not by God himself.
In essence, then, by appealing to pagan gods rather than the Christian God, Hrothgar and his council are simply prolonging their agony. After all, we also know that their enemy Grendel is a child of Cain, one of the sons of Adam, part of the Christian belief system, and he cannot be defeated by appeals to a religion--paganism--that no longer has any power.