The world is increasingly saturated with a proliferating number of so-called "gender identities" and it's undergirded by a nefarious ideology that is an assault on the image of God, specifically how human beings are male and female. How can and how should Christians engage this and what is the bigger picture as described in Scripture? Catholic University of America moral theology professor John Grabowski unpacks that and more in his new book "Unraveling Gender: The Battle Over Sexual Difference."