St.Anselm proposed two versions of ontological argument for God’s existence.The first is well known.But it is confronted with Kant’s notorious criticism,i.e.“existence is not a predicate”.In a modern logical perspective,this version of ontological argument is not even qualified as a well-formed inference,for its premise is not a proposition or sentence but a propositional function.So there is no question of its being valid or sound.The second or modal version of Anselm’s ontological argument was “discovered” by Charles Hartshorne and Norman Malcolm.Hartshorne’s modal version of ontological argument is doubtful in its two premises,one of which looks upon “exist necessarily” as a predicate,while the other explicates possibility with conceivability.We do not think the first premise could get round the Kantian criticism.As to the second premise,ontological possibility cannot be confused with logical possibility,and with too thick psychological character,conceivability is not fit for explaining ontological possibility.Malcolm’s version of the modal argument gives a justification for the second premise,i.e.Anselm’s Principle.Malcolm’s strategy is interpreting modality in terms of tense.But in our opinion,modality and tense each fall into different philosophical categories.The study of ontological arguments shows the application of modern logic playing a key role therein.The key role manifests itself in the shift of linguistic paradigms in the study of philosophy of religion and the selection of logical inference rules.All in all,the logical analysis of ontological arguments indicates that both construction and development of ontological arguments depend on the correct application of logical techniques and means very much,and as to whether logic can be applied correctly in the study of religious philosophy,it lies on whether one has true knowledge of some important philosophical problems of logic or not. St.Anselm proposed two versions of ontological argument for God’s existence. The first is well known. But it is confronted with Kant’s notorious criticism, ie “existence is not a predicate.” In a modern logical perspective, this version of ontological argument is not even qualified as a well-formed inference, for its premise is not a proposition or sentence but a propositional function. So there is no question of its being valid or sound. The second or modal version of Anselm’s ontological argument was “discovered ”by Charles Hartshorne and Norman Malcolm. Hartshorne’s modal version of ontological argument is doubtful in its two premises, one of which looks upon “ exist necessarily ”as a predicate, while the other explicates possibility with conceivability. We do not think the first premise could get round the Kantian criticism. As to the second premise, ontological possibility can not be confused with logical possibility, and with too thick psychological character, conceivability is not fit for explaining ontological possibility. Malcolm’s version of the modal argument gives a justification for the second premise, ie Anselm’s Principle. Malcolm’s strategy is interpreting modality in terms of tense.But in our opinion, modality and tense each fall into different philosophical categories. The study of ontological arguments shows the application of modern logic playing a key role in. The key role manifests itself in the shift of linguistic paradigms in the study of philosophy of religion and the selection of logical inference rules. All in all, the logical analysis of ontological arguments indicates that both construction and development of ontological arguments depend on the correct application of logical techniques and means very much, and as to whether logic can be applied correctly in the study of religious philosophy, it lies on whether one has true knowledge of some important philosophical problems of logic or not.