[__z]

>Let the state make rules around civil partnerships, and let religions deal with marriage

That's exactly how it works now. One is called civil marriage and one is called religious marriage. The church sets their own rules and the government sets theirs. You can be in one, the other, or both at the same time.

Civil marriage is a legal contract, religious marriage is decided by the church and it is whatever the church says it is. The government lets clergy also officiate civil marriage but it doesn't have to. It does because it makes sense. You wouldn't have to need a civil official and a religious official at your wedding. You wouldn't have to go through two ceremonies, one at the church and one at city hall.

Don't put too much thought in the fact that both contain the word "marriage" in them.

Goodrich vs. Dept of Health (MASS.) (emphasis mine):

"Marriage is a vital social institution. The exclusive commitment of two individuals to each other nurtures love and mutual support; it brings stability to our society.... The question before us is whether, consistent with the Massachusetts Constitution, the Commonwealth may deny the protections, benefits, and obligations conferred by civil marriage to two individuals of the same sex who wish to marry. We conclude that it may not. The Massachusetts Constitution affirms the dignity and equality of all individuals. It forbids the creation of second-class citizens.... the arguments made... failed to identify any constitutionally adequate reason for denying civil marriage to same-sex couples."