In a recent post, Eugene Volokh briefly analyzes a Colorado Civil Rights Division decision that a bakery didn’t discriminate based on religion when it refused to bake a cake with an anti-homosexuality message:

Colorado law bans discrimination only when it is based on “disability, race, creed, color, sex, sexual orientation, marital status, national origin, or ancestry.” This means that a store may not specifically refuse to sell cakes to gays, or sell them to (say) Baptists. It may well mean that it may not specifically refuse to sell cakes for use in same-sex marriages, or in Baptist events. It may even mean that it may not specifically refuse to inscribe messages that identify buyers as gay (e.g., “John and Bill’s marriage”), or as Baptist (e.g., “Baptist Church Picnic”).
 
But nothing in the law bans discrimination based on ideology more broadly. (The ban on “creed” discrimination in such laws is simply another way of banning discrimination based on religion, as courts have held.) A store can refuse to sell to someone because he’s a Nazi, or a Communist, or against abortion rights, or pro-abortion rights, or pro-gay-rights, or anti-gay-rights. A store can likewise refuse to inscribe cakes with Nazi, Communist, antiabortion, pro-abortion, pro-gay-rights, or anti-gay-rights messages, if it’s discriminating based on the ideology of the message, rather than the religion of the buyer.
 
Here, the agency found — plausibly, I suspect — that the baker was upset by the anti-gay message, and would have objected to it regardless of whether the customer or the message was religious. (I read the “derogatory language and imagery” quote from the agency as descriptive, and not legally necessary; the store would have been equally free to reject messages that it saw as unpatriotic, or supportive of the wrong sports team, or anything else.) No discrimination based on religion, no violation of the law.

For more on the facts of the story, also see ABC 7 News Denver.