The major reference to religion in this poem is through the description of the way that the speaker imagines the star to watch the seas endless retreat and drawing in around the shores of the world. Note how this is described in lines 5-6:
The moving waters at their priestlike task
Of pure ablution round earth's human shores...
"Ablution" is a word with religious connotations, refering to ritual washing or being cleansed, which imbues the waters of the sea with a mystical quality as if they have the power to cleanse the world of man from its sin and wickedness. These lines create an image of religious purity which is twinned with the following two lines, that suggest purity through the way that snow covers up human land. Both of these sights the star from its vantage point views and surveys. The image of snow covering land and making the landscape pure and white is another image that is used in the Bible frequently to describe the ritual cleansing and process of being forgiven for sins. Both symbols of purity serve to highlight the special status that the star has and also accentuate its mystical qualities as being an object that looks down on earth and is eternal.