I have seen Jason Evert’s book, and I know people who have used it, but I am not familiar with it myself, so I can’t speak for it. As for your principal’s concern, I’m not sure from which angle she’s coming from. Certainly, as a doctrine closely affiliated with personalism, TOB at least hopes to be the antithesis of a dualistic separation of soul and body. For example, in JPII himself, you can see his criticism of Manicheanism in the General Audience for October 15, 1980 (Waldstein translation 44:5-6). And he continues this train of thought in the following audience (45:1-2), where he says that Christ’s words condemning lust are “the affirmation of the body as an element that, together with the spirit, determines man’s ontological subjectivity and participates in his dignity as a person…The body in its masculinity and femininity has been called ‘from the beginning’ to become the manifestation of the spirit. It becomes such a manifestation also through the conjugal union of man and woman when they unite with each other so as to form ‘one flesh.’”
But even stronger for practical purposes, I think, is the Audience of April 15, 1981 (Waldstein 60). There, the Pontiff says: “We cannot consider the body as an objective reality outside of man’s personal subjectivity… Practically all the problems of the ‘ethos of the body’ are at the same time linked with the body’s ontological identification as the body of the person and with the content and quality of subjective experience, that is, at the same time ‘living’ both one’s own body and in interhuman relations, particularly in the personal ‘man-woman’ relation.”
These statements are particularly important in light of what the same Pope would say later in Veritatis Splendor, the only Encyclical in the history of the Church to deal exclusively with the teaching of Moral Theology. A good chunk of that encyclical was written to combat the revisionist moral theorists, who posited that bodily acts and the use of exterior objects were “premoral”; that is, since morality has to do with the will, a particular bodily act can’t be judged as good or bad apart from a consideration of intention; in itself, if does not yet belong to morality. Such thinking led to the denial that various actions in the area of sexuality were really wrong in themselves. They could be right and good, for instance, if the two people really loved each other or something. Veritatis Splendor hits this theory hard. In doing so, these words are included:
“To separate the fundamental option from concrete kinds of behaviour means to contradict the substantial integrity or personal unity of the moral agent in his body and in his soul” (VS 67).

The conclusions that John Paul II comes to are the same as the conclusions that St. Thomas would hold. Since man is lord of his own acts through his reason and will, whenever he performs a voluntary exterior action, if it is disordered,it is sinful by the very fact that the man did it; it’s not as if reason and will only command the spiritual acts of man. JPII goes about it from a very subjective, phenomenological, anthropological approach in TOB. St. Thomas goes about it from the approach of order to an end, acting according to reason, and “faculty psychology” (in Veritatis Splendor, this approach is actually pretty strong, too). JPII’s approach in TOB has the ontological unity of soul and body in the person as one of its most important cornerstones. In fact, morality for him includes a kind of call to constantly become more conscious of this unity in one’s actions (see Waldstein 10:4). This is not so important for St. Thomas. For him, whether you were thinking deeply or not, if you did something that was according to reason, you did good. If you did something that was against reason, you did bad. For St. Thomas, morality is about ordering yourself to your last end, and only accidentally about affirming what you are. But in TOB, the affirmation of the ontology of the human person, in its soul-body unity, is exceedingly important. Thus, I’m not sure how it would be ever able to separate the body from the person. Indeed, the phenomenological approach of TOB rests on the fact that the human body is the only way we can have access to the person experientially; if it turns out that the body is not the person, then TOB has nothing any more to say about morality.

I am hoping to use Theology of the Body for Teens by Jason Evert for my middle school students this year. I teach in an ecumenical Christian school, so, of course, some of it will have to be modified or deleted. I gave the book to my principal, and after skimming it, she said her main problem with it–as well as with all the “sex ed.” books we have purchased–was that it treated the body as separate from the person. I know this is not true, but could you please help me show her that it is not? I haven’t read TOB, but we have a copy if there is a particular section to which I should point her….

Thanks for your help! God bless.