I sent this to my MP (Julian Huppert, LD, for Cambridge) this morning. I deliberately took a different line from the usual one because I'm well aware that Julian doesn't need persuading on this but it may be useful for him to have more ammunition of the form "Catholics are not quite such a unified block as it may appear".
Yesterday at Mass it was suggested to us that we might like to support a campaign to preserve the current legal definition of marriage (I forget exactly which campaign). This is of course in line with what our bishops tell us. But this Catholic does not support the party line; and I felt it important to write to you in favour of equal marriage, although I know you've already publicly stated your support for it.
Campaigners against equal marriage, including many Catholics, seem to feel that it is in some way a threat to their existing marriage or their existing way of life. Allowing consenting adults to marry even if they happen to be of the same sex poses no more a threat to my marriage than allowing the marriage of black people, or people past the age of having children, or people who happen to be taller than me. I do not fear it, and indeed I can see no respectable reason why I shouldn't welcome it wholeheartedly. The support of a verse of scripture (amid many other prescriptions rarely followed nowadays) and some dubious claims about what is "natural" are little more than unconvincing fig leaves for a fear of what is different, and the Catholic hierarchy should be ashamed of its un-Christian attempts to cast as many of the first stones as possible.
I rather suspect that the current reactionary point of view of a number of traditional religions, including my own, will come around eventually. Judging from carefully-phrased comments one of our priests has made when he's been required to read a bishops' letter on the subject, not even all of our clergy are as reactionary as it might seem today. In the meantime, it is the right thing to do for the state to move on without them.
(It occurred to me some time after sending this that "casting the first stone" was a poor choice of scripturally-inspired metaphor, because Christ didn't say that the woman caught in adultery hadn't sinned, only that he didn't condemn her. That wasn't what I intended to imply. Nevertheless, getting the Catholic church to bless equal marriage is clearly a bridge too far at the moment; for now it would be enough if they simply got out of the way.)