I … want to read more about why a baker refusing to serve a gay couple over “religious beliefs” is actually bigotry and NOT freedom of expression.

As you wish.

Let’s assume that a bakery open to the general public lists cupcakes on the menu of items offered to any customer that walks in the door. A customer can buy cupcakes that have already been decorated in a generic way at a reasonable price, but for an equally reasonable extra charge, a customer can buy cupcakes that are decorated according to a customer’s wishes (within reason). That bakery also happens to exist in a state where the law says that bakery can’t discriminate against people in specific protected classes, such that the bakery can’t refuse to sell items on its menu to a gay person because that person is gay. Put a pin in that point, because it’s going to be important in a moment.

Two customers walk into the bakery at separate times on a given day (let’s say one in the morning and one in late afternoon) and each want to buy some cupcakes. The first one wants a box of pre-decorated cupcakes and is openly signaling their queerness⁠—e.g., they’re wearing a Pride T-shirt⁠—so there is no mistaking that they’re gay. The second one, who is actually straight, wants a box of cupcakes with custom decorations that include a Pride flag. In both instances, the bakery refuses to sell both customers the product they want: with the first customer, the bakery refuses to sell the cupcakes at all; with the second customer, the bakery refuses to sell only the service of putting the custom decoration on the cupcakes. In both instances, when brought forth to a court in a lawsuit, the bakery’s owner cites their religious beliefs about queer people⁠—which includes citing all the usual “clobber verses” from the Bible⁠—in explaining why he made those two refusals.

Now, here’s the $64,000 question: Even though both decisions are driven by religious bigotry, what makes only one of them a clear-cut violation of the law?

The key here is a two-word phrase: “compelled speech”. The Constitution of the United States contains the First Amendment, which offers protection to all citizens against government intrusion into the right to express speech and ideas freely. That means the government generally can’t stop someone from expressing a shitty idea like “gay people don’t deserve to live” no matter how much a hell of a lot of people would love for the opposite to be true. On the flipside of that same coin, the government also generally can’t force (“compel”) people to express themselves in ways that violate their conscience; in practice, that means the government can’t force an anti-gay bigot to say “gay people deserve to live” even under threat of punishment.

The law says that when people are in a protected class under the law, a public-facing business (e.g., a bakery that is open to the general public) can’t discriminate against those people based on the trait that puts them in a protected class. If sexual orientation is such a trait, that means a public-facing business can’t refuse to sell to a gay person any good or service from its menu (literal or metaphorical) that it offers to straight customers. (And before you think to say it: Yes, the inverse holds true as well, because the law protects the majority as well as the minority even though the majority rarely needs such protections.) But one of the very few exceptions to that rule involves expressive speech. In general terms, the government can’t force the employees/owner of a business to express speech, even on behalf of a third party, that goes against their conscience. The details do matter, such as whether the business has a blanket policy against hate speech, but in broadly generalized terms, the law lets businesses refuse to express speech they otherwise wouldn’t. (Incidentally, this principle also comes into play with online spaces, as the law also allows a website to dump speech its owner doesn’t want to host on their site and do so without legal penalty.)

Our hypothetical bakery refusing to sell cupcakes to a gay customer because that customer is gay violates the law because those cupcakes⁠—which only have generic decorations⁠—were on offer to the general public and refused to a gay customer despite the law saying that gay customer is part of the general public. The bakery refusing to decorate the straight customer’s cupcakes with Pride flags likely wouldn’t be against the law because of protections against compelled speech⁠—and that would likely hold true even if the bakery admits to not putting those decorations on those cupcakes due to an anti-gay bias. Both acts, as laid out in my comment, would be an example of religious anti-gay bigotry. But one of them would (most likely) be legal because while the state can force a business to serve gay people (and with good reason), the state can’t force the owner of that business to say “gay people are great” even if they’re only saying it on behalf of someone else. Gay people are as much a part of the general public as anyone else, and as with people from other protected classes, they deserve the same treatment in open-to-the-public businesses as everyone else. But no one should have the right to compel pro-gay speech from anti-gay bigots.

…and I suspect you’ll ignore all this with “lol tl;dr” so you can wallow in the muck of your continued intentional ignorance. C’est la vie.