No priests and nuns do not think sex is unholy. THey have in themselves decided to devote their lives to Christ and remain chaste. In fact, the Pope wrote a book on love and far from being against "sex", it was encouraging to married partners as God Himself created it. How then could it be unholy? God Himself told us to all be "fruitful and multiply" it is meant to be enjoyed, as well as for two people to take part in the incredible act of procreation (as well as bonding).

It is how it is used and outside of marriage, according to the bible is a sin (fornication). Since God created it, He knows best where it is best....well....exercised. But yes, perhaps this is better discussed on the other forum.