While camping at the World Youth Day vigil in Kraków this summer, I spoke with a young woman who was preparing to enter her first year of college at a prestigious university in California. She pulled her iPhone out of her backpack and showed me where her online college application required her to check the appropriate box to indicate her gender. There were 18 boxes to choose from. I read through the litany of genders, and noticed that two were missing: male and female. (Facebook—which invites its users to identify as one of 58 genders—at least offers them the possibility of choosing to be male or female.) The university application, however, did allow the incoming students to choose “cis-male” or “cis-female,” which means that the biological sex one was assigned at birth aligns with the gender one chooses as their identity. What’s going on? Where is this coming from? In a sense, it could be said that Gaudium et Spes prophesied our culture’s sexual identity crisis by stating, “when God is forgotten the creature itself grows unintelligible.” In order to offer pastoral care for individuals who struggle with gender dysphoria, it is useful to reflect upon the roots and ultimate goal of gender theory. Throughout its history, the Church has defended the truth of the human person from ideologies that aimed to separate the body and soul, including Gnosticism, Manichaeism, and Cartesian Dualism. In varying ways, each of these schools of thought pitted the physical against the spiritual, considering what is material to be inferior to what is immaterial. Similarly, gender theory promotes the notion that one’s gender is a reality that exists independently of one’s body, and it defines one’s true identity. In other words, one’s body is not a reliable guide to discovering one’s identity. Rather, the body is a collection of parts that may be augmented or even surgically removed if they conflict with one’s internal feelings.