The Ontological Argument for the Existence of God

[Jenny A]

Anselm's contempararies immediately noted that the same logic could be used to prove the existence of a maximumlly anything from islands to grasshoppers. David Hume argued that that no particular thing necessarily exists. It has also been noted that maximumlly great is an incoherent idea as it leads to questions  like could such a being make an object too heavy for it to lift. Kant objected to the use of existence as a predict. 

But, the OP's rendition seems to be missing a crucial couple of steps notably:  that to be maximumlly great a being must exist.  And it is this missing step that all but one of the above critisms address.  As is the OP's conclusion doesn't follow from his premises.