The religious dimension that is so important in this novel is shown through the impact of Calvinism, and in particular, the doctrine of predestination. This is shown through the vexing question of whether Jack Boughton is able to repent and change his life, even after all of the bad things he has done. The way that Jack Boughton returns to Gilead strikes a parallel with the parable of the prodigal son, who similarly returns after living a life of decadence and hedonism elsewhere. Robinson clearly foregrounds the theme of forgiveness by naming the town that he returns to Gilead, which refers to the balm Jeremiah looked for that would heal the injuries suffered in conflict. Jack, through choosing to return to his hometown, is searching for similar balm, and a similar healing as he desires to be reconciled.
The problem is that John Ames, Jack's godfather, has to do some serious thinking before he can extend his blessing and forgiveness to his godson. The conflict that he faces is trying to struggle between his own human feelings of frustration, jealousy and dislike, coupled with his beliefs in Calvinistic theology, with God's love and grace, which he acknowledges knows no limits, as this following quote demonstrates:
There is no justice in love, no proportion in it, and there need not be, because in any specific instance it is only a glimpse or parable of an embracing, incomprehensible reality. It makes no sense at all because it is the eternal breaking in on the temporal.
The religious dimension of this novel therefore plays itself out in this internal conflict faced by John Ames III, as he struggles to forgive and to show the same kind of love and grace to his godson that he himself realises he has been shown, and is continued to be shown, on a daily basis. Just as "there is no justice in love," Ames needs to realise that whatever Jack has done in the past, the love that he deserves as one of God's creatures should be unconditional.