As far as I'm aware when a cleric conducts a marriage they are performing two roles: the religious one, obviously, and the civil/legal element on the same basis as a registrar conducting a civil (non-religious) marriage.
Aside from the shameful ring-fencing of the C of E under SSM legislation in England & Wales I'd have thought that religious organisations declining to conduct SSM to those who meet the legal requirements to marry might consider opting out of the civil element altogether (since they can't discriminate if they aren't providing the civil element to anyone) and restrict themselves to doing a post-civil religious ceremony - else they provide the civil element without discrimination.
I think you are forgetting that vicars of the Church of England are automatically licensed to perform marriages and have a register in their Church. Other Churches like the Roman Catholic require a registrar to be present they are not automatically allowed to marry people.
In the Church the vicar has the right to say who he marries. Because he has his license due to the fact he is a vicar and for religious purposes.
The vicar believes marriage for a man and woman so religiously will only marry a man and a woman.
That is because he believes that marriage outside God and a man and a woman is not marriage.
For legal purposes two people of the same sex can marry. But it is a legal ceremony with no definition in religious beliefs.
I am not sure why everyone cannot just accept the truth for what it is.
In Gods eyes there is no marriage outside that of a man and a woman.
In the eyes of the world anyone can legally marry now.
Are people saying they can change God and what he teaches?
That would not be honest, truthful or based in trust in God and his word.
We are being ridiculous if we think we can change everything to suit man. Adam and Eve tried it, mistrusted what God told them and look how that ended up.... HERE....