You seem to think "discrimination!" is the be-all and end-all of U.S. legal theory. In some cases you ARE allowed to assert your constitutional protections over the consideration normally due to others.  Sorting this out is why the case has made its way to the SC.

People can SAY anything about what their religion demands. We've already been over this issue;  convincing a court is something else, again.  You would be hard-pressed to find a church doctrine that supports not serving blacks, but would have no trouble at all finding mainstream church marriage rite procedures referencing "holy matrimony", "ordained by god", "union of man and woman", etc., etc.

We've also already been over the injury involved, and it is not the baker being "offended". Ironically, the "solutions" you suggest entail significant injury to the baker for adhering to his religious principles.  Being coerced into an illegal agreement is not binding; again, the SC will decide.