What if the baker (or sign writer) were to say that "content of a pornographic, religious or political nature will not be accepted" ? I think I may have seen something like that and this cake business may explain it.

It is illuminating to read through the posts that come below the link to the judgement. Several very outspoken people clearly have not read it and are talking nonsense.

This quote (from the EHCR if I understand correctly) immediately had me thinking of many below the line discussions:

"The Court re-iterates that, as enshrined in Article 9, freedom of thought, conscience and religion is one of the foundations of a 'democratic society' within the meaning of the Convention. This freedom is, in its religious dimension, one of the most vital elements that go to make the identity of believers and their conception of life, but it is also a precious asset for atheists, agnostics, sceptics and the unconcerned. The pluralism indissociable from a democratic society, which has been dearly won over the centuries, depends upon it. "