There are times when it is perfectly fine to discriminate. If you’re casting a movie about Abraham Lincoln, you have every right to not hire a short Asian woman for the part (unless you want to for some artistic reason). If you’re looking for someone to teach the Bible to students at a private religious school, you have every right to demand that person believe in the same religion as you. If you have started a private club for “Children of Italian-American immigrants” then you have every right to keep out anyone else. It’s not really discrimination when it’s a required qualification.
The preference of your customer base is not a “qualification.” Years ago, airlines only hired women to be flight attendants, pointing to surveys that showed their customers preferred to be served by women than by men. No, the court ruled, that’s not a “qualification.” Customer preference to be served only by women (or by white people or by Christians) doesn’t matter because rights are not voted on. A majority of Americans didn’t want schools integrated either when the courts ruled that they must, but that doesn’t mean the majority was right.
You can’t create qualifications that are simply there to discriminate and don’t have a rational relationship to the position. For instance, groups like the Jaycees and the Rotary Club used to exclude women from joining. Why? No real reason. The Supreme Court saw through that, pointing out that the goals of the club had absolutely nothing to do with things that only applied to men.
While you have the right to start your own private club (Freedom of Association. It’s there in the 1st Amendment), you don’t have the right to discriminate in public accommodations. Hotels, clubs, stores, and restaurants and other places are not allowed to discriminate and that means your club meeting in these places can’t discriminate when there isn’t a qualification. Having these groups meet on your own personal property? Probably fine.
Yeah, that’s a gray area, but in general, you can’t create a group that discriminates for no reason. “The Christian Men’s Group” could discriminate if indeed they are doing things that are applicable only to Christian men, but if they’re just a front for an organization whose real purpose is to provide business networking while keeping out non-Christians and women, then probably not.
What about private clubs that discriminate by having a bodyguard stand outside and decide who gets in? Perfectly fine so long as the reason for denying entrance isn’t based on race or sex or anything prohibited by the 14th Amendment. You technically don’t have a “right” to visit a club or shop in a store, which is why these places can deny service if you’re disruptive or don’t meet their dress code (no shoes, no shirt, no service) or have some other reasonable reason not related to things prohibited by the law.
Recently, a member of a group called the “Sad Puppies” — butthurt snowflake selfish white male Trumpites who whine about things like the 1% of female leads in science fiction — was barred from attending a major science fiction convention after he stated that he planned to take disruptive action at the convention, having done similar things in the past. So of course, he claimed he was being “discriminated against” because of his political views. But no, it’s not “discrimination.” A private organization has the right to deny entry to anyone they think will disrupt their group, including for political disruptions.
There’s also been a group of men who claim that they are being discriminated against by women who refuse to have sex with them. I am not making this up. These entitled jerks call themselves “incels” for “involuntarily celibate.” (I know, sounds like an Onion satire, doesn’t it?) As if women owe them sex simply because they’re men. These guys have their own web pages and everything where they whine about how terrible it is that nobody wants to have sex with them. These idiots are not being discriminated against.
And just a few days ago, a judge ruled that it wasn’t discrimination for a bar to throw out a guy wearing a “Make America Great Again” hat, especially because they didn’t want to have to deal with fights and arguments in their establishment.
Remember, you have every right to hold whatever terrible political viewpoints you want. That is guaranteed to you under the Constitution. You don’t have the right to demand that anyone else provide you with a place or a forum for you to express those opinions, nor do you have the right to demand that someone let you into their group when they believe you don’t meet their standards. No shirt no shoes no service.
If you choose to be the kind of guy people can’t stand to be around and they say they don’t want you near them, that’s not discrimination. You chose to be that person.
As Frank Zappa said, “It’s okay to discriminate against assholes, because nobody was born an asshole.”