Is God ontologically masculine?

Yes. God is masculine in His very being. Masculinity and femininity are ontological realities of the soul rather than facts about bodies, so the fact that God has no body does not make Him any less masculine. Yes, and "ontologically masculine" is the right way to say it. It is better than saying He merely has masculine characteristics, because characteristics are things you can have or lose. Ontology is about what a thing is. Start with the distinction that most of this argument turns on: sex and gender are not the same thing. Sex, in the plain old sense, refers to bodily organs. Gender is ontological, meaning its being is not dependent on anything else; it simply is what it is. You are either male or female, and there is no in between. Your body does not make you what you are. Your soul was made masculine or feminine, and your body complements your soul. Both are masculine together or both are feminine together. There is no confusion and no third option. Masculinity and femininity go deeper than chromosomes and genes, deeper than the XY factor, because they are in the soul. Once you see that, the objection from God's incorporeality evaporates. People quote Catechism 370, that God is pure spirit "in which there is no place for the difference between the sexes." Take the word "sexes" seriously and the sentence is unobjectionable: God does not have a body, so He does not have the organic apparatus that distinguishes male and female bodies. That is true and no Catholic disputes it. But that statement is about sex, not about gender. Just because God does not have sex organs, because He is not a body as we are, does not mean He cannot be male. Male is a gender, and gender comes with the territory. It comes with being God. I would add, as a general caution, that on ordinary matters, baptism, the Eucharist, marriage, the 1997 Catechism is reliable, but on out-of-the-ordinary and more esoteric subjects it needs to be read carefully, and this is one of them. Scripture is entirely consistent on this. God the Father is masculine, Jesus Christ is masculine, the Holy Spirit is masculine. The Father and the Son are always referred to with masculine language, without exception. The Holy Spirit is the one place where there is some grammatical give: in the New Testament the Spirit is usually referred to with the neuter, though there are a few places where the masculine pronoun is used. In the Old Testament the Hebrew ruach can be feminine as a free-floating noun, but where it matters most it is not free-floating. In the construct phrase ruach Elohim, spirit is bound to Elohim, and Elohim is masculine, so the whole construction is necessarily masculine. People who build a feminine Holy Spirit out of the gender of a Hebrew noun are building on sand. What about the passages where God compares Himself to a mother? There are a handful, Isaiah among them, and they are genuine. But look at the grammar. The operative word is "like." In Hebrew that is the kaph prefix, in Greek the hos. It does not say God is a mother. It says God acts as a mother acts in this particular respect. That is a simile, and a simile is precisely a statement that two things are not the same. That is about as close as Scripture ever comes to calling God a mother, and it is not close at all. There is a corroborating case that most people miss. The angels are pure spirits with no bodies at all, and Scripture always presents them as male; no female angel is ever named or described. Their male gender is ontological, not organic, exactly as God's masculine gender as Father is ontological. So we already have a whole order of bodiless creatures whose masculinity is not a matter of anatomy. If it works for them, the objection that a spirit cannot be masculine has no force. I want to say one more thing, because this is usually heard as a demotion of women and it is the opposite. If femininity is ontological, then a woman is not a woman because of her body parts. Her body parts are the result of her being an ontological female. She has feminine characteristics of being that men simply do not have. That gives a woman far more dignity than the modern account does, which reduces her to anatomy and then lets her trade it in. And this is exactly where the present confusion comes from. Once you say the only difference between men and women is organs, you have already conceded that a man with the right surgery is a woman. The whole gender ideology follows from a metaphysical mistake, and it has already reached how people translate the Bible and how they speak of God the Father. Recover the metaphysics and the confusion has nowhere to stand.