Mix It Up at Lunch Day is one of those programs that just seems like a nice thing to do.

The idea is that on one day of the school year, kids are invited to have lunch with the kind of kids they don't usually hang out with: the jocks mix with the nerds, lunch tables are racially integrated, et cetera. Sponsored by the Southern Poverty Law Center as part of their Teaching Tolerance division, it arose out of a broad effort to tackle the problems of bullying in the schools and bigotry in society – and it appears to have been effective in breaking down stereotypes and reducing prejudice. Over 2,000 schools nationwide now participate in the program, which is set to take place this year on 30 October.

You can argue about how permanent its effects are, or whether other approaches might be better, but the idea of making new friends in the lunchroom seems utterly benign. Right?

Wrong, as it turns out – at least, according to the American Family Association, a radical rightwing evangelical policy group. Mix It Up at Lunch Day is, in fact, part of "a nationwide push to promote the homosexual lifestyle in public schools", according to the AFA literature. The program "is an entry-level 'diversity' program designed specifically by SPCL (sic) to establish the acceptance of homosexuality into public schools, including elementary and junior high schools," warns the AFA website. "See if your child's school is on the list."

The AFA has urged parents to keep their kids home on 30 October, and claims that at least 200 schools have responded to its charge by canceling the program.

There's a backstory here. The Southern Poverty Law Center, which has fought for civil rights causes since its founding in 1971, conceived and promoted Mix It Up at Lunch as part of their Teaching Tolerance program. The SPLC also, as it happens, named the AFA, along with a dozen other "pro-family" groups, as a "hate group" in 2010, citing, among other factors, AFA's expressed views on same-sex relationships. The "homosexual agenda" is not the only factor in the SPLC's decision to include AFA on the list. AFA's director of issues analysis, Bryan Fischer, has appeared to suggest that what is biblically deemed "sexual immorality" merits punishment by death. He evidently hates Muslims, too, having recently opined that "allowing a mosque to be built in town is fundamentally no different than granting a building permit to a KKK cultural center".

So, now it's payback time. The AFA's jihad against Mix It Up at Lunch Day is its way of saying "I'm rubber, you're glue." It has come up with its own list of boycotts and hate groups, and sure enough the SPLC, on account of its "incendiary language", is on that list.

Funny word games aside, the SPLC is right. It is, by now, well known that the AFA and the kind of interests they represent spread conspiratorial falsehoods about the LGBT community, placing blame for a wide variety of social ills on a "gay agenda". They also seem to support a certain type of bullying and bigotry in public schools – the faith-based kind – and believe there should be more of it.

One example comes from an AFA cultural ally: Gateways to Better Education, formed in 1991 by Focus on the Family in tandem with a rightwing Christian legal advocacy group that calls itself the Alliance Defending Freedom (ADF). Gateways publishes a "Guide for Commemorating Religious Freedom at School". But the freedom Gateways and the ADF have in mind applies only to those who share their religion.

"Religious Freedom Day is not 'celebrate-our-diversity-day,'" members are reminded. Gateways advocates a "Biblical approach to tolerance", which apparently consists of intolerant attitudes toward what the ADF and Gateways call "pro-homosexual education" and "the gay activist agenda". Parents' No 1 goal, they say, should be to "encourage your children to be bolder" in expressing their faith at school.

The far right's fixation on same-sex relationships is so ludicrous that it defines a sub-category of camp. But let's take a step back for a moment. The big question, the one that keeps coming back in every one of these skirmishes in the culture wars, is: why is the loudest religion in American politics today so much about hate?

Consider Mix it Up at Lunch Day from the perspective of the almost limitless other conceptions of the Christian religion that are out there. You could, for example, construe it as an exercise in "loving thy neighbor". You could quote the gospel of John that "God is love." You could view it as part of the religious mission of charity. I have no doubt that there are countless Christian and non-Christian people in the US who would view Mix It Up Day in just this way.

So why does the form of religion that seeks to claim the term "Christian" in the political realm have to focus so relentlessly on a "gay conspiracy" – not to mention sexually active singles and the purely evil Muslims?

I don't believe for a moment that this hysterical voice that screeches in America's political sphere is the authentic voice of religion in America. Most religious Americans want to mix it up at lunch! They want to make friends across party lines, and they want to help people who are less fortunate. A survey by the Public Religious Research Institute, released on 24 October, reveals that 60% of Catholics believe the Church should place a greater emphasis on social justice issues and their obligation to the poor, even if that means focusing less on culture war issues such as abortion and same-sex marriage. Earlier this year, in response to the Ryan budget, the United States Conference of Catholic Bishops joined other Christian leaders in insisting that a "circle of protection" be drawn around "essential programs that serve poor and vulnerable people".

So why is it that the so-called "values voters" are urged to vote against the politician who supports choice, not the politician who wants to shred that "circle of protection" for the poor and vulnerable? Why is it that when politicians want to demonstrate just how religiously righteous they are, they talk about banning same-sex marriage and making contraceptives hard to get, instead of showing what they have done to protect the weak?

There is an obvious answer, and it is, in a sense, staring you in the face every time you watch a political debate or read about the latest antics of Focus on the Family and the AFA. The kind of religion that succeeds in politics tends to focus on the divisive element of religion. If you want to use religion to advance a partisan political agenda, the main objective you use it for is to divide people between us and them, between the in-group and the out-group, the believers and the infidels.

The result is a reduction of religion to a small handful of wedge issues. According to the religious leaders and policy organizations urging Americans to vote with their "Biblical values", to be Christian now means to support one or, at most, a small handful of policy positions. And it means voting for the Republican party.

This type of rhetoric is also championed by a segment of Jewish conservatives. Alarmed that Obama won 78% of the Jewish vote in 2008, they accused Democratic Jews of being "Jinos" – Jews In Name Only. "They eat bagels and lox; they watch 'Schindler's List,'" writes Town Hall columnist Ben Shapiro, "but they do not care about Israel" – at least, not in the way that Shapiro thinks we should.

When religion is thus reduced to a single policy decision and support for a political party, it becomes shrill and bigoted. This abuse of religion for political purposes has been tremendously damaging for American politics. But it is worth pointing out that it has been destructive of religion, too. According to another poll this month, this one by the Pew Research Center, record numbers of Americans are now reporting that they have no particular religious affiliation. Perhaps that is because, right now, the God of hate seems to be shouting louder than the God of love.