The late Pope John Paul II says couples can tell a lie with their bodies. What does he mean?

Sometimes one or both do not give themselves completely to the other but instead use the other selfishly, as a pleasure object. Treating the other as an object is divisive rather than unitive.

There are several ways men and women can reduce one another to the status of object. Sex between couples who are not married and therefore do not bring a total commitment to their union are, in the Holy Father's terminology, telling a lie with their bodies, because their bodies speak a language of total, unconditional, and permanent self-giving when in fact they are doing nothing of the sort.31 In that sense, their sexual expression becomes a lie, because it misrepresents their relationship. Regardless of their feelings for each other, their sexual expression promises more than it objectively delivers.

Married couples who are committed to exclusive, permanent, and unconditional love may also tell a lie with their bodies when they separate the procreative aspect of sex from the unitive through contraception. Here, the failure to give oneself fully is more subtle but nonetheless real.

Deliberately frustrating the procreative aspect of a sexual act creates a condition that makes self-giving only partial and reduces the spouse, in some degree, to a pleasure object used for selfish purposes. Thus, marital love must be exclusive, unconditional, permanent, and open to life.