This is an undeniably religious book, but its religious elements can be understood through literary analysis. To paint his mother as the Christian Messiah is simultaneously to honor and dishonor his mother, because it honors her in the most utmost way by revering her in the station of a goddess, because Jesus is considered purely divine in the Christian religion. Yet, because they are Jewish, Asher's commentary is about the suffering of the Jews, and his shame includes the confusion he feels about religious tradition, because he's confusing the imagery of two religions, artistically.
The disapproving father is another somewhat religious motif, because of what fathers tend to represent in traditional home, especially in Hassidic Jewish communities. This father is no exception. Clearly he worries that art somehow breaks the male identity that the father wishes the son would voluntarily accept, as it is the father's inheritance to him in some way. But, the father doesn't realize that by perfectly misunderstanding his son, he is slowly making Asher feel like an orphan.
The idea of God is what is ultimately depicted in the dying mother image of Asher's final, heralded magnum opus. His own mother hung on a cross, for him. This message of religious sacrifice is coupled with the fact that ultimately, it was his mother who gave him life. Therefore, if his mother is dying, that is a religious omen of his own inevitable death. That means that he sees God in the imagery, because he sees his own death and is left calculating the value of his mother's love and sacrifice.
