Please note that I have not suggested that a civil union is the solution. I was responding to a question from McGrath, in which he asked why is it seen as unacceptable for different human partnerships to have different names? I answered that it would be perfectly acceptable [but unnecessary] provided that each kind of partnership brings its members the same rights.

The latter part is the key: a civil union must give the participants all of the rights that they might derive from a legal marriage performed (as is common in the US) by a Justice of the Peace. If someone wants to be sprinkled, blessed, or whatever by the clergyperson of their choice, that is an entirely separate matter. It follows then that if a civil union is identical to a marriage, no purpose would really be served by having separate names, other than to mollify the feelings of people who think a certain segment of the population is not entitled to use one word or the other.

The issue is the rights each partner to the association has, not whether you say "John is married to Ralph" or "John is Ralph's partner". And who is harmed if one says that "Mary is John's partner" rather than "Mary is married to John"?