Evangelicals and others who protest civil unions or gay marriage as somehow going against the enduring tradition of a sacred institution are wrong for many reasons. But now a historian has uncovered evidence that civil unions between gays was sanctioned in Medieval Europe. Somewhere long ago I read a preface by Gore Vidal making the same case. Apparently these gay marriages didn't destroy the sanctity of anyone else's marriage, as is often predicted by today's fire breathers (who seem unable to stop soliciting sex in men's rooms from undercover or off-duty cops).
Our "sacred" tradition of marriage has little resemblance to the "sacred" tradition of marriage just a few centuries ago, when the idea of choosing a mate out of love was regarded as preposterous. You chose a mate for financial or security reasons if you were in the upper class, or you married a mate chosen for you by your parents, or you were bought and paid for.