Silas could feel his homeland testing him, drawing violent memories from his redeemed soul. You have been reborn, he reminded himself. His service to God today had required the sin of murder, and it was a sacrifice Silas knew he would have to hold silently in his heart for all eternity.
Silas stands for the capacity of the Church to change people completely, an important idea in the novel. The Church made a concerted effort to erase people’s belief in the divinity of women and nature, stressed the idea of female original sin, and promoted the ultimate authority of the Church. The Church is so successful at changing entire societies that it can take commonly held ideas—such as the idea that sex is something to enjoy—and turn them into taboos. Brown suggests that Sophie’s horror and disgust at seeing her grandfather in the act of sex is a product of the culture she grew up in, not a fundamental human instinct.
In order to prove that the Church, and faith itself, can change the way men operate, Brown demonstrates how faith and Bishop Aringarosa’s attention give purpose to the murderous Silas. All the Church does, however, is give Silas an excuse for killing. Silas justifies murder by telling himself he is killing in the name of God. He does not hesitate when the Teacher asks him to kill people in the name of finding the Grail and (he thinks) saving Opus Dei. Silas has come to believe that the Church and God are so important that any action taken on their behalf is acceptable.