Let us remember Arthur's final speech before he leaves Camelot on the barge that will take him to Avilion to be restored. Note what he says to Sir Bedivere, the only knight he is in attendance on him:
If thou shouldst never see my face again,
Pray for my soul. More things are wrought by prayer
Than this world dreams of. Wherefore, let thy voice
Rise like a fountain for me night and day.
For what are men better than sheep or goats
That nourish a blind life within the brain,
If, knowing God, they lift not hands of prayer
Both for themselves and those who call them friend?
Arthur asks Sir Bedivere to pray for him and to remember his soul, pointing towards the overwhelming efficacy of prayer to enable his restoration and return to the land of the living. This, according to Arthur, is only a natural response of those who truly understand God and "know" Him and his power. Thus, symbolically, although King Arthur is about to depart the land, his spirit, or the kind of values and beliefs that he symbolises, can return as he is metaphorically resurrected through our prayers and faith in God. In this poem it is important to remember that Tennyson is hearkening back to a Golden Age of England, but also, through Arthur's words, he is indicating that the same kind of values that made that time so special can be resurrected in us today if we have faith enough in God.