In her impressive Atonement, Eleonore Stump claims that her novel Marian theory of the atonement meets a desideratum for a successful theory that Aquinas's theory does not, namely, showing that Christ's passion and death are essential to the solution to the problem of human sin. Here I suggest reasons to side with Aquinas, who says that Christ's suffering and death are not necessary, but merely a fitting way of solving the problem. If the fittingness of Christ's passion and death is a good enough justification for it, we lose a motivation for adopting the Marian theory over the Thomistic one.