You're correct that all government recognition of marriages is "civil" in the sense that the government is the civil authority. Still, marriage is a perfectly accurate word to describe this civil union, and it can apply equally to gay and straight couples. There is no need to create a separate civil union system rather than expanding the government recognition of marriage. Indeed, separate systems for stigmatized minorities have a terrible track record.
Also, you say that "Civil unions give gays the same legal and property rights as those in a 'marriage' ". While "civil unions" could give the same rights as "marriages", the fact is they don't. The rights conveyed by civil unions differ among the states that grant civil unions, and the federal government under DOMA withholds certain rights from gay couples in civil unions or marriages.
Marriage is religious, a religious union of a man and woman, what we call "marriage" in the United States and other countries is a legally recognozed civil union for property rights, legal and power of attorney purposes.
I say keep marriage religious and in the hands of churches and let civil unions be formally recognized.
Marriage laws differ by state too, no different that civil unions, the fact is that civil unions aren't second class, they're fully legally recognized under state laws. the gays are simply wasting time and money arguing over a damn word, not rights.