Unlike God and the golden carp, the Virgin of Guadalupe offers up forgiveness. The Virgin serves as a connection between the cultures that pull at Antonio, even though it's a traditional Catholic symbol.
How does that work? Well, the Virgin is deeply rooted in Catholicism, sure, but her appearance took place in the New World—where Catholicism mixed and mingled with regional spiritualities. In that sense, she's directly linked to the land and the heritage of Antonio as a son of that land.
But once again, Anaya ensures that there's more to it than just that. The Virgin also symbolizes the power of women to nurture and forgive, much like Mary does in the New Testament. Antonio says of the Virgin Mary, "She always forgave. Perhaps the best god would be like a woman, because only women really knew how to forgive" (13.42-44). We're not sure what that says about gender relations, but we can't help but notice that in this novel, the dude's got a point.
How so? Well, Tenorio meets his bitter end because he's unable to forgive Ultima for her supposed hand in his daughters' deaths. But Ultima, forgiving him as one of her last acts, dies a much more peaceful death. Maybe we can't chalk all that up to the fact that she's a woman, but the contrast is there to be sure.