The abandoned sister
One of the clearest symbols in the story is the beloved sister who threatens to kill herself if Godric leaves her to live in the real world without her. What she represents about his character is his cold-bloodedness, because he still goes. No one in the story is as attached to him as she is, but he is not attached back to her. She also might represent community, because he prefers his life as a ne'er-do-well, alone. Even in the world, he is alone, because he is constantly manipulating the masses.
The blood of the martyr
When Godric sees the symbolic conundrum at the church, he finds a man who died honorably, and instead of mourning the death or being amazed by the drama of religion, he sees dollar signs. He drains the martyrs blood and sells it as a religious relic to the people in town who buy things like that. This symbolizes his immunity to religious ideas. He isn't scared of divine judgment, and he knows that religious people in his village are likely willing to believe whatever he can sell to them. He sees through the religion.
The blood of the cat
When he runs out of the blood of a human, he realizes that it's impossible to tell one animal's blood from another, so he kills a cat. He sells the blood of the cat and lies. Now, his thirst for money and his willingness to bend rules has crossed a threshold. He has taken life, and he has begun lying outright for money. The blood of the cat is a dark, witchy symbol, because he has taken a turn down a dark road of religious hypocrisy.
Gilian the mystic
God should absolutely reject this sinner, right? But instead, Gilian the mystic finds Godric and invites him into a relationship with the God whom he has rejected. She doesn't point him to the aspects of religion that typically attract other people; instead, she invites him into religious mystery. Isn't life mysterious itself, without religion? Existence is too strange and synchronous for Godric to ignore. He realizes that the plot of his life seems to be fateful and ordained, and he suddenly realizes that he does believe in God after all. It's just organized religion that he dislikes. He becomes a mystic like Gilian, having learned from her that mystic religion has greater depth than popular religion.
The mystical allegory of evil
Through the story, Godric realizes what the reader realizes by reading his story: his life is an artistically designed narrative, an allegory, pointing thematically back to the unimaginable strangeness of reality and the human experience. His willingness to do evil leaves him in the mood to contemplate, because he isn't even remotely innocent. His hands are covered in blood, and if God's justice is coming after death, he wants to figure that out now and learn how to pay his recompense while on earth. Evil drives him toward a mystic religion that good, rule-following Christians in his village don't understand, because he doesn't resort to belief until he is certain.
