But that's just it:
No baker, not even Mr. Phillips, would ask a straight couple about their sex life or drinking habits or whether the couple gambles. It would be considered rude, an invasion of privacy. The baker would soon be out of business.
But, bakers such as Mr. Phillips don't need to ask rude questions of a gay couple. The evidence of the couple's "sin" is standing right in front of the offended baker. Two men. Asking about a wedding cake.
Years ago, I saw a TV news story about racial discrimination. A young woman called an apartment building manager about an apartment for rent. The landlord said he had a unit available. The young woman said the moment she opened the manager's door and walked in, the manager's whole demeanor changed. The manager no longer cared about the woman's income or previous rental history, etc. All the manager cared was that the woman was black. The manager told the woman the apartment was rented. Days later, the "for rent" sign was still out front.