“Before we get started,” Roxane Gay told the packed auditorium of the keynote she was giving at Emory Univeristy alongside Erica Jong to kick off the Decatur book festival in Georgia, Friday night, “something important has to happen. Because today is a very special day. Can everybody hear?”

Then, over the first notes of a Beyoncé song she played from her phone, Gay playfully asked, “Whose birthday is it?”

Jong laughed genially as the audience shouted back, “Beyoncé”.

But then she could not resist correcting Gay. “May I just remind you that Beyoncé walks in the shoes of Billie Holiday and Ida Cox, the great blues women,” Jong said. “most of whom were African American, who created feminist poetry in this country.”

Erica Jong in 1976: ‘We have a long tradition of women of colour being feminists’ Photograph: Evening Standard/Getty Images

While some audience members clapped, others shifted uncomfortably at the disconnect between Gay’s light-hearted opening and Jong’s seriousness. It was the first of many awkward moments in an evening that, while meant to celebrate feminism, ended up illustrating its generational, cultural and racial divides.

Jong is a scion of second-wave feminism and the sexual revolution, having gained national fame with her wildly popular 1973 debut novel, Fear of Flying. This week, to much anticipation, she released a follow-up of sorts, Fear of Dying. Gay, meanwhile, is still enjoying the success of her 2014 essay collection, Bad Feminist, which has been at the forefront of what is becoming a national discussion of culture and identity.

At first glance it seemed like an ideal pairing for a discussion about feminism’s place in American culture. And indeed, for the first portion of the conversation, Gay and Jong chatted fairly amiably about feminism’s emerging accommodation of older women and Jong’s own identification with Clarice Lispector, Virginia Woolf and Charlotte Brontë.

But when the audience was invited to ask questions, things got tense again. A barely audible young woman asked a long, multi-layered question that Gay paraphrased to the audience as, “How do we make sure that feminism becomes more and more inclusive and accounts for more than just white women?”

In her answer, Gay said, “Feminism has to realise it’s really about intersectionality … but that word tends to be off-putting. That just means that we inhabit more than one identity. I’m not just a woman. I’m Haitian American. I’m Catholic. I’m from Nebraska. I have a body. I have tattoos. I mean not all of these identity markers matter as much as others.

“You have to think about how there are multiple barriers for equality for some women. That it’s not just gender. It’s also sexuality, class, race, ethnicity, ability. And we have to take these things into account. We have to realise that just because we’re women does not mean we’re equal.”

Jong’s response began rather differently. “I also want to say that anybody who says that feminism is only a white thing is ignorant of the history of feminism,” she began. She mentioned blues singers, black abolitionists, and black female civil rights leaders, “who were all passionate feminists beyond any white women you could name”.

Jong said she thought anyone who claimed otherwise was speaking from “historical ignorance. “We have a long tradition of people of colour, of women of colour, being feminists,” Jong insisted. “A long tradition.”

When Gay agreed but reminded Jong that mainstream feminism has historically excluded women of colour, the audience clapped. Jong, apparently taken aback, demanded: “And I don’t know – are you talking about me?”

Gay answered simply, and almost consolingly, “No.”

Jong went on to say, “Because I can tell you that in my history I was called, like you, a bad feminist. In the 70s I was called a bad feminist by many people because I liked to wear lipstick and I liked to wear high heels and I thought men were cool and I liked to wear fancy underwear. So that’s just bullshit. I mean it’s ignorance.”

Gay responded: “Yes, but I think we’re speaking beyond – it’s not about us. Just speaking about feminism, like some of the current concerns of feminists.”

As the audience mumbled, Jong then insisted: “Current concerns of feminism are multiple, many. And number one, women with brown or black skin have been passionately involved in feminism from the beginning. Two, we recognise that.

“Gloria Steinem when she started Ms. magazine made people know who Sojourner Truth was,” Jong continued. “People didn’t know about her before. This white movement began popularising these figures who had been buried.”

The rest of Jong’s response included her assertion that the Black Lives Matter movement (referred to in the original audience question) was “a political movement trying to show us our failure of empathy, and as such I salute them”. And she was adamant that reading black writers was important, as was reading “African and European and British and Caribbean and whatever” writers. “But let’s not confuse animals,” she urged. “Feminism has always been interested in people of colour, in my view.”

Now, it was Gay who off-handedly mumbled, “OK.”

Jong added: “We may not have achieved that glorious heaven where we all join hands and love each other, but we have all recognised the problem and are working toward it.”

“All right, we’ll take another question,” suggested Gay, as the audience laughed and clapped.

Later, when another audience member asked both Gay and Jong if either had been influenced by either Mae West or Moms Mabley, the drama intensified. Gay mostly demurred on the response with a simple “No”.

Jong gave a lengthy answer, crediting West for being “a great old broad”. Then Jong asked, “And who is Mabley?” An audience member shouted a sarcastic reply: “She was a great old black woman broad.”

At the very end of the evening, Jong and Gay agreed that feminism might reach a point where difference will not be an obstacle. They both also agreed that it would take a lot of time and a lot of work to bridge the divide.

“But it’s not going to be work for people of colour,” Gay emphatically said. “We’re good.”

The talk left audience members, among them several prominent novelists and poets, tweeting their frustrations at Jong’s comments:

Erica Jong also claimed "no one" would know about Sojourner Truth had it not been for Gloria Steinem writing about her. Oh word? #dbf2015 — Saeed Jones (@theferocity) September 5, 2015

Tonight's @DBookFestival keynote in a nutshell: @rgay says "intersectionality" and Erica Jong says, "What's that?" — Rachael Maddux (@rachaelmaddux) September 5, 2015

Jong simply added the following response on Twitter: