The Cathar view of procreation
The Cathars held the view that marriage and procreation of children were sinful. They also taught that the world was ruled by evil and was evil in itself. With this in mind, it makes perfect sense that the Cathars held marriage and procreating children in contempt.
The very nature of the Soul is Joy, an ecstasy that is likened to a staggeringly powerful orgasm. This ecstasy is a gift of God, of the Spirit that created the Soul in its own image. To direct such feelings down into the body and out of itself is to direct our very nature into the world of duality and form, i.e. the physical world. Children are the product of orgasm, but rather an orgasm that is directed towards the physical world. Instead of using the sexual power inherent in each of us to experience our True nature in Union with the Spirit of God, we use it to divide what should not be divided—ourselves. The result is children.
Physical procreation of children seems just another painful manifestation of the endless suffering that goes on in the physical realm, itself an endlessly changing series of changes that simply does not change into anything as eternal as the never-changing process of change itself.
