Gödel's ontological proof certainly derives its conclusion correctly from its axioms. But the problem isn't only that the conclusion isn't really "God exists" if you want that to match the god of any actually existing religion; it's also that the axioms are ... well, let's just say "not obviously true".
In particular, he relies on this notion of "positive properties". It is not at all clear that there is any notion of "positive properties" that satisfies his axioms, still less one for which "positive" is actually a good name.
(The axioms are certainly false if, e.g., we take "positive" to mean something like "regarded as good by some particular person" or "regarded as good by a majority of intelligent and thoughtful people". Gödel wants the conjunction of all positive properties to be positive, which in particular implies that it isn't outright impossible. But it's easy to find properties generally regarded as good that are not mutually compatible.)
In particular, he relies on this notion of "positive properties". It is not at all clear that there is any notion of "positive properties" that satisfies his axioms, still less one for which "positive" is actually a good name.
(The axioms are certainly false if, e.g., we take "positive" to mean something like "regarded as good by some particular person" or "regarded as good by a majority of intelligent and thoughtful people". Gödel wants the conjunction of all positive properties to be positive, which in particular implies that it isn't outright impossible. But it's easy to find properties generally regarded as good that are not mutually compatible.)