Our civilization developed as a Catholic civilization. It developed and matured as a Catholic thing. With the loss of the Faith it will slip back not only into Paganism, but into barbarism with the accompaniments of Paganism, and especially the institution of slavery. It will find gods to worship, but they will be evil gods as were those of the older savage Paganism before it began its advance towards Catholicism. The road downhill is the same as the road up the hill. It is the same road, but to go down back into the marshes again is a very different thing from coming up from the marshes into pure air. - Hilaire Belloc, "The New Paganism"
Belloc points out elsewhere that slavery is the default economic position of society. It was Christian culture that eventually abolished slavery, but we are always tempted to fall back into it.
I would say (and I have said) that we will do the same thing with sex. The default cultural position of society is the spiritualization of sex by a dark spirit: sex infested with demons. Much as we like sex, once we ignore God and make it the center of our lives, far from becoming a fun and liberating thing, it becomes violent, perverse and filled with occult ritual and significance.
But we miss the fleshpots of Egypt (see Ex. 16:3).