[swatcoder]

> Because many Christians to varying degrees don't see marriage as a legal construct (whether exclusively, primarily, or at all, depending on the person), but as a religious one

It's not quite so simple, though. In most countries without a state religion or with modern humanist foundations, they already recognize it as both.

Pedantic Catholics wouldn't recognize the religious validity of a marriage involving a divorced person blessed by a different church, but they don't challenge the legal validity.

Likewise, almost all Christians accept the legal validity of a marriage involving two hetersexual Muslims or atheists, even while rejecting that it carries the same religious validity as their own.

Most are totally accustomed to the difference between legal marriage and religious marriage and that requirements for such marriages vary. Their resistence to homosexual marriage has other roots.

[dragonwriter]

> Pedantic Catholics wouldn't recognize the religious validity of a marriage involving a divorced person blessed by a different church, but they don't challenge the legal validity.

A pedantic Catholic would note that the Church actually presumes the religious validity of non-Catholic marriages between people who are non-Catholics, even though such marriages would be invalid for a Catholic, and while the issue of prior divorce makes this a more difficult question, it only does so because it then requires a definitive resolution of the presumed validity of the former marriage.

This is not-infrequent source of complications if one of the partners, after divorce in the second marriage, seeks to marry a Catholic in the Catholic Church, so its a fairly well-documented issue, if perhaps obscure to people who aren't pedantic Catholics.