In Chapter 2, Gertrude has a heavy feeling about her new-born infant. "'My lamb!' she cried, softly. At that moment she felt, in some far inner place of her soul, that she and her husband were guilty."
"A wave of hot love went over her to the infant. ... With all her force, with all her soul she would make up to it for having brought it into the world unloved. She would love it all the more now it was here, carry it in her love."
"She thrust the infant forward to the crimson, throbbing sun, almost with relief. ... Then she put him back to her bosom again, ashamed almost of her impulse to give him back again whence he came."
"'I will call him "Paul",' she said, suddenly, she knew not why."
I take this to be an allusion to the Apostle Paul's first letter to the Corinthians, where he says: "Get rid of the old yeast, that you may be a new batch without yeast-as you really are. For Christ, our Passover lamb, has been sacrificed. Therefore, let us keep the Festival, not with the old yeast, the yeast of malice and wickedness, but with bread without yeast, the bread of sincerity and truth."
Gertrude names her son after the apostle. She thinks of him as a sacrificial lamb, bearing the sins of the hatred between her and Walter. Like the sacrificial lamb, she offers her son back to God. Then, recognizing she must bear her sins on her own, she longs for a fresh start - free of the malice and wickedness she has experienced with her husband; filled with a relationship of love for her son founded on sincerity and truth.