In the news this week, a woman in Kentucky has claimed to become a Catholic priest. This is, of course, an utterly ridiculous claim. Dressing up like a priest and putting on a show does not make you a priest.
The truth of the matter is that the Catholic Church cannot make a woman a priest, even though some of its members would like to. Whenever the sacrament of holy orders is performed on a woman, it does not take effect. That is to say, her soul remains completely the same and does not change one bit. When the sacrament of holy orders is performed on a man, it takes effect, and his soul changes to conform with that of Jesus Christ the priest. The priest's new soul is what allows him to delegate the sacraments in the person of Christ.
Jesus Christ, who knew that only a male soul (like his) could be united to his in priesthood, decreed that only men could become priests. In the same way, Jesus Christ knew that only a female soul could be united to his in a spiritual marriage, and he decreed that only women could become brides of Christ.
That is the reason why women cannot become priests. It is contrary to the nature of the female soul. Needless to say, people who don't believe in the soul or the ontological change of the priesthood find this explanation uncompelling. They tend to argue that the ban against female priests is a human invention, with no basis in the reality of the soul. They say that Jesus did not allow for female priests, because he was conforming to the culture of the time. Two problems with that argument:
1. There were female priests in the culture of the time.
2. Jesus never cared about conforming to the culture of the time. In fact, he preached quite eloquently against being led by the world.