Final answer:
The texts provided suggest a thematic focus on human relationships and an appreciation for nature over traditional religious faith. Without the actual text of 'Lullaby', however, it's not possible to analyze the speaker's belief in God or lack thereof in that particular poem.
Step-by-step explanation:
The poem 'Lullaby' is not explicitly discussed in the provided text, which makes it challenging to determine how the speaker shows a lack of belief in God throughout the rest of the poem. However, if the poem in question aligns with the overall themes expressed in the texts provided, one could argue that there is a focus on human relationships and experiences over divine faith.
In the quotes from Wordsworth and W. B. Yeats, we see an emphasis on nature, human emotion, and personal transformation rather than conventional religious belief. Wordsworth's speaker in 'The World Is Too Much with Us' expresses a preference for a pagan connection to the divinity of nature over the modern world's detachment from it. Similarly, the characters in the other texts are preoccupied with human love and personal infidelity, rather than a spiritual faith. These thematic elements suggest that faith in human love and nature take precedence over traditional religious belief.
The analysis of the poem's rhyme pattern or line structure requires the actual text of the poem, which is not included. Hence, a definitive answer to questions about specific formatting and refrains, as well as the poem's detailed exploration of concepts like 'purity' and 'sin', cannot be provided without access to the poem itself.