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.
Two words used in this poem refer to its religious imagery. The first word is 'Eremite' in the fourth line and the other word is 'ablution' in the sixth line. 'Eremite' means a hermit, usually with religious connotations. The bright star is presented her as a hermit. The words 'patient' and 'sleepless' may refer to a hermit's meditation. The bright star is 'steadfast' in the sky and look like a hermit. Secondly, the word 'ablution' means 'religious cleansing' or 'ritual washing'. The rise and fall of the tides daily here stands for the religiously performed rituals.
In lines 4 to 8 Keats presents the star as gazing down at the snow (which stands for beauty). The star is steadfast but it is isolated. The poet wishes to be 'steadfast' like the start but not as isolated as it is. He wants to enjoy the physical beauty which the star can only gaze at.