I know this is Britain; but, I have been waiting for this to happen someplace ever since the “gay marriage” thing got going. At some point, some gay couple will sue a church for not marrying them on the grounds of a “hate crime”. It will happen here.
It already is. The argument is that churches are “places of public accommodation,” and thus subject to the civil rights laws (e.g., you can’t legally refuse to serve someone in your restaurant if he’s black, etc.)
The proponents of this theory argue that if a church ever lets non-members in to worship (for example, at a Christmas or Easter service, just as an example), it becomes subject to the civil rights laws and cannot discriminate against homosexuals. The only way for churches to avoid this, they argue, is essentially to become a private club, where only members are permitted to worship there.