 In the coming discussion, it will be supposed that the targets are atheists and agnostics, and that the goal is to turn them into theists. Suppose that an advocate presents an ontological argument to a target. What conditions must that arguments satisfy if it is fit for its intended purpose? A plausible suggestion is that, minimally, it should make the targets recognise that they have good reason to accept the conclusion of the argument that they did not recognise that they have prior to the presentation of the argument. Adopting this plausible suggestion provides the following criterion: a successful ontological argument is one that should make atheists and agnostics recognise that they have good reason to believe that God exists that they did not recognise that they have prior to the presentation of the argument. Note that this criterion has a normative dimension: it adverts to what atheists and agnostics should do when presented with the argument. 