As Mrs. Thomas demonstrates, religion is used to reflect a faith or belief in the afterlife.  Religion is a means by which individuals can find some hope in a world that is not of this world.  This means the religion is a form of escapism.  This is incompatible with Bigger's frame of reference, which is locked in the present tense.  In this setting of the here and now, there is an immediacy that religion does not address.  Bigger cannot bring himself to reconcile his struggles with the present in a larger configuration that religion offers.  It is here where Bigger cannot accept religion.  Its role is one that is in his life, present in his mother and those who believe in it.  Yet, Bigger rejects it because it does not allow him to transform the world to which he is bound.  Bigger is a product of the present tense, something for which religion and "the afterlife" cannot fully find use.  In the Chicago of the Depression, there is only a struggle for survival in the here and now.  Bigger is a product of this, and his instincts for survival are ones that preclude him from embracing religion, which cannot provide explanation as to why things are the way they are in the present.  It is for this reason that he ends up rejecting religion as something that will not help him do the one thing that he finds it hard to do:  To live.