Our invitation to be part of Gods act of creation. The early church was Greek in its early philosophy. To the ancient Greek understanding culmination of the sexual act resulted in the temporary annihilation of reason, and anything that destroyed reason was bad.
I think that the Jewish understanding takes a more mystical view that it is not destruction of the intellect that happens, but that the shared creative act of a Husband and wife allows you, for a moment, to participate in or experience the joy God feels at the goodness of his creation. (Happy to hear the comments of any Rabbi on this point!)
Not a rabbi but I could play one on TV...
Mystically, in the works of Kabbalah and Chassidut, pro-creation is being a partner with G-d. To take part in this act, akin to creating ‘something from nothing,’ touches the essence of pleasure, so it flows from there that it [is pleasurable, etc....]
Biggirl, from one of your posts (ie, JC and the Church....) you might say, ahem, G-d and the Jewish people.
Re: Go forth.... a little joke: Why is the first commandment given from G-d to man “go forth and multiply?” Because when man saw how fun the first commandment is, he’d want to keep ALL of the commandments! (rim shot, please)