Can you think of any reasonable secular reason why two sensible adults who love each other shouldn’t be able to say so, committing solely to each other in the sight of all their friends and families? I’m racking my brains and I can’t.
If you can’t either and you live in the UK please consider going to this web page:
http://www.homeoffice.gov.uk/publications/about-us/consultations/equal-civil-marriage/
The government of the UK are actually consulting the citizens of the country about their feelings on extending the possibility of civil marriages, as opposed to civil partnerships, to those who want them. In addition anyone who would like to change an existing civil partnership to a marriage will be able to do so.
This does NOT mean that churches will be forced to marry anyone they do not wish to marry. Nor will they lay themselves open to prosecution by such refusals. This shouldn’t make a ha’p’orth of difference to those religious organisations who would not agree to conducting such marriages.
It shouldn’t make a difference but you can bet it does and that the Home office is getting a good number of “OMG the cities of the plains!!1!” responses to the consultation. If you believe that every human being has the right to love and be loved by another consenting adult of whatever sex, gender, orientation, then please take some time to fill in the online consultation form. It would be a terrible pity if the only people who did it were the haters.
Elin Gregory 
Amen to that.