In chapter 8, Gatsby describes the time when he (along with other soldiers from his army camp) first met Daisy. He fell in love with her and felt a "breathless intensity" about her house, as it was suffused with mystery. He describes her in terms that make her seem like an untouchable goddess. For example, before he must leave her, he touches the ends of her fingers gently. To him, her house is like a temple, pervaded by mystery and the wonders of great wealth.
The reason that Fitzgerald brings these religious-like memories that Gatsby has of Daisy into chapter 8 is that they remind the reader why Gatsby is willing to sacrifice himself for her. She is not just human to Gatsby; instead, she is sacred to him. Nick tells Gatsby to leave his house to avoid the trouble surrounding Myrtle's death, but Gatsby won't leave until he knows that Daisy is safe; ultimately, this means sacrificing himself for Daisy.