The argument csn not be made that gay marriage is offensive to most people. Polls disagree.
It does not matter.

Politcal groups and terrorist groups are not protected. It does not matter that they are offensive or not, not one has to make politcal or terrorist cakes. It is ridiculous to think they do. 

I really do not understand your point. 

You can look up protected classes here:
https://www.colorado.gov/pacific/dora/civil-rights/cases-we-handle

I do not see political groups or terrorist groups in there.