Human sexual and religious practices are diverse in history.
What is commonly counted vice, may once have been considered virtue. The opposite is also true. But this variation in moral practices does not mean that morals are worthless; it only shows the ingenuity with which human society has adapted itself to the needs of its environment. In every society, some norm must be settled on, and accepted by all.
The experience of time confirms the relative worth of one practice over another; and despite our modern priggishness and righteous judgments, longevity confers some measure of positive social utility.