We got a little off-topic last time, but that's fine, we got some good discussions out of it. I have another reason why Buddhists shouldn't have orgasmic sex.
In my previous post on this subject, I explained how orgasmic sex causes addiction, which clouds our minds and stops spiritual growth. If you do not have a mind free from addiction, you cannot see the world as it really is, and therefore you are unable to understand it. This is key to wisdom in Buddhism.
A big part of Buddhism is to avoid suffering. Some would say it is the most important part. The goal of Buddhism is to identify the elements in our life that make us unhappy (ie. suffer), and get rid of them.
Orgasmic sex is intoxicating. The orgasm itself is like a drug. As I have mentioned before, we have to distinguish between intoxication and happiness, because intoxication causes suffering. Non-orgasmic sex is much less intoxicating, and therefore causes less suffering.
Why does intoxication cause suffering? Well, that is well-described in Marnia's book. The ups and downs of orgasmic sex causes us to behave in patterns that are directly counterproductive to happiness in many ways.
Comments and questions are welcome.