For believers, against the unbeliever

Quoting B.M. Bonansea in agreement with Karl Barth’s contention that Anselm’s Proslogion was never attempting to stand outside of faith and prove to an unbeliever: #presuppositionalism

More precisely, the argument is not meant to convince an atheist or an agnostic - no theistic argument will ever do so - but only those who have been enlightened by faith and are favourably disposed towards it. It is true that in his reply to Gaunilo’s objections Anselm writes: ‘It was a fool against whom the argument of my Proslogion was directed.’ However, this does not mean that the argument was written for a fool but rather against a fool, i.e, one whome we would today call an unbeliever.

This supports the contention that the theistic proofs have value, but not primarily in the persuasion of the unbeliever but in the strengthening of the believer against the wiles of unbelief.

Necessity of an Ontological Proof

Kelly proposes that some kind of “ontological proof” is necessarily hidden in every system of thought.

Rather, the point is this: systems of thought that reject the Holy Trinity need some other ultimate reference point to make their system work; some necessary thing. It would appear that truly ultimate reference points impose themselves; that is, they have to be ‘ontologically assumed’ although this will not usually be stated (not is it necessarily conscious in most cases).

References

Kelly, Systematic Theology - Volume 1 , p. 69, 75
[[ B.M Bonansea, Man and His Approach to God in John Duns Scotus ]], p. 175
See also the relevent discussion of Hilary on the foolishness of unbelief