The public mostly have frowned upon sexual intercourse as a part of worship. The Catholic Church finds sex rites too carnal in nature, and has no connection in achieving divinity and spiritual growth. However, in Wicca, sex rites have always been considered as a divine union of the God and the Goddess. They call this the Great Rite, and is mostly performed by third-degree initiates. The Great Rite most often characterized the unity of two opposite deities into one omnipotent source of energy.
Furthermore, the Great Rite symbolizes fertility and produces a great amount of energy between two participating parties. The Great Rite can either be actual or symbolic. Some covens use their magick tools, the anthame and the chalice to imply union of the God and Goddess. Traditional covens however still practice sex magick rites to create more intense magickal power between the union of the spirits exercising the ritual.
It is malicious that people from different spiritual backgrounds find it ex magick abusive and immoral. To Wiccans it is a sacred act, not everybody in a particular coven can perform the actual Great Rite. As mentioned earlier, only priests and priestesses who have gained much experience with rituals and magick can perform it.
They have a deeper understanding behind the sexual intercourse that is about to transpire between them. There should be no sexual attraction between the initiates who are going to partake with the Great Rite. Yes, sexual intercourse is an experience, wherein humans derive pleasure from, but in Wicca, it is so much more than that. The Sex Rite is a ritual wherein love emanates from those who participate in it. This positive energy flows from separate individuals, and at the peak of the act, is united into one cosmic heap of energy.
Even though the act of the Great Rite had already been explained, there are still some who see it as inappropriate. Wiccans of today are having such a difficult time explaining these rituals to non-believers. Wiccans are spiritual people who believe that the main purpose of Wiccan spells and magick are geared towards harnessing great amounts of energy and turning them into positive manifestations and outcomes. Sex is still considered a taboo for even the most Westernized individuals, and the idea of a performing sex as a religious activity is still a big no-no to a majority of people.
It probably will take time for all of mankind to understand the sacredness of the Great Rite. For now, Wiccans are still positive that someday, people will appreciate the symbolism behind the ritual and find beauty, and not the vulgarity of sex as a sacred human activity.