The issue is not Religious Freedom for the Church of England. Marriage only between a man and a woman is for the whole of society.

The French rabbi Gilles Bernheim whom the Pope quotes with approval argues:

The idea that marriage should be made available to all who love each other is unsustainable. Loving a person does not give you the right to marry them: a man cannot marry a woman who is already married; a woman who loves two men cannot marry them both. We cannot, in the name of equality, allow to marry to all those who love each other; ‘marriage for all’ (‘equal marriage’) is therefore merely a slogan. The legalisation of same-sex marriage would continue to ‘discriminate’ against all those people who love each other but who are not allowed to marry

The slogan ‘marriage for all’ (‘equal marriage’) conceals the fact that what is being proposed is a radical new vision of marriage to replace the existing one.

In the traditional, conjugal understanding of marriage, with which most people would agree, marriage is not simply the recognition of love; it is an institution which binds the union of a man and woman to the succeeding generations.

The real problem here is how harmful this bill would be for our society as a whole, and how, whilst benefiting a very small minority, it would irrevocably blur three crucial concepts:

 

These are the core issues which should be openly tackled when debating same-sex marriage and same-sex parenting, because they take us back to the ground rules of the society in which we all want to live.

 

I believe that human beings cannot grow, if they are denied structures, order, a status, and guiding principles. I believe that promoting freedom does not mean doing away with all limits. That promoting equality does not mean eradicating differences. That the very power of technologies and imagination means we must never forget that life is a gift, that is will always be there before us, and has laws of its own.”

 

http://cvcomment.org/2013/01/25/frances-chief-rabbi-what-has-been-forgotten-in-the-debate-on-gay-marriage/