The Boxes of Sexuality model

Sexuality: What we experience relationally in our day-to-day interactions with others. Our sexuality propels each of us to desire genuine relational connection with God, others, and a potential mate. Sexuality also includes our general sexual desire and gender makeup, masculine and feminine. This is the large box we all live in—whether we want to admit it or not—because we are all sexual beings.

Erotic Sexual Behaviors: These are actions (both physical and mental) that are romantic or erotically arousing, such as fantasy, sex talk, kissing, and caressing.

True Sex: Those most intimate of erotic sexual behaviors that are biblically reserved for marriage between man and woman (Hebrews 13:4). At minimum, “true sex” includes all intercourse behavior (oral, anal, vaginal) and mutual orgasms. However, true sex may include other erotic sexual behaviors as well—especially those including genital expression.

(from the Definitions and Models, pp. 11-12)