This past weekend I presented the workshop, "Homosexuality: Always God's Children" at the Credo retreat. We did not have time for the Q&A portion of the workshop, so the questions will be answered here during the next week or two.
Q: By saying a same-sex marriage is ... incomplete? because they cannot be fruitful, how would you argue a man and a woman who are incapable of having a child?
A: This is a very common question and an important one to ask.
First, let's note that if a married couple is unable to consummate their marriage through the sexual act, then they are not able to marry in the Catholic Church. This isn't because sex is the most important aspect of marriage, but because our bodies reveal the invisible, and the sexual act expresses the free, total, faithful and fruitful love of marriage in a unique way. A same-sex couple is incapable of consummating "marriage" with the sexual act.
A couple who is infertile, on the other hand, is still capable of the sexual act. It is usually devastating for couples who cannot physically have children, but whether or not they are physically able to conceive does not determine the fruitfulness of their marriage.
Fruitfulness is always first spiritual. But because our bodies speak a language and make the invisible visible, if our bodies are closed off to human life (whether through a same-sex action or through contraception), then this says something about our openness to being spiritually fruitful.
So, whether or not someone has a child, or even how many children they have, cannot indicate the spiritual fruitfulness of their marriage. But, conversely, an incapability of engaging in the action that leads to physical fruitfulness indicates something about the couple's ability to live marital spiritual fruitfulness. We need both unity and difference to be fruitful. Because we are a unity of body and soul, this is expressed in and through our bodies and the sexual difference we have been given.
Another difference is that many couples who struggle with infertility still conceive. Perhaps it's a matter of diagnosing the main problem, of timing, of stress, etc., but many couples have waited 3, 6, 8, 10 years or more to conceive before they finally did. For a same-sex couple, this possibility will never exist.