Season 5 centered on a story about an Islamic State cell in Germany planning a terrorist attack in a subway station.
The day before the show was set to film the season finale in 2015, a group of terrorists armed with assault rifles and explosives carried out coordinated attacks in six locations across Paris, killing at least 130 people and wounding hundreds.
"You can imagine the kind of stuff that was running through our minds as we were doing that," Gansa told CNN in an interview. "And the responsibility we felt telling a story like this and wondering if we told the right story, or if we had done it in the right way or if we were somehow sensationalizing this stuff."
This led to what Gansa called "soul-searching," the result of which he feels can be seen in the upcoming sixth season.
The new season is set in the period between a presidential election and the inauguration -- a choice motivated by the writers' desire to highlight "an incredibly fragile time in our democracy."
"It seemed like a nice, tense 6 or 7 weeks of time to set the season in," Gansa said. (CNN's interview with Gansa took place about two months before the presidential election.)
The incoming president is a woman named Elizabeth Keane (Elizabeth Marvel), who is "a little Bernie, a little Trump, [and] a little Hillary," according to Gansa.
Meanwhile, protagonist Carrie Mathison (Claire Danes) is back in New York City, working in a new career.
"I think the last thing we want to do is posit another attack on that city we all love," Gansa said of the new setting. "We're not going to do a terrorist attack in New York. We don't want to pile on in terms of the fear that is ... so prevalent in our culture right now."
So what are they doing? No spoilers. But it suffices to say this season's story "will focus on a much different aspect of intelligence gathering than we have in the past," Gansa said.
"In the past, it's been about 'Are we going to stop the attack or not?' And this season is going to be different," he said.
As always, the story was influenced by the writers' annual trip to Washington D.C., where they met with intelligence experts, White House staffers and journalists.
After those meetings, Gansa said he often walks out with his mind "fairly blown" and "wondering about the world." Creatively, they're inspiring.
Season 6 marks somewhat of the beginning of the end for the decorated Showtime series. Last August, the show was renewed through Season 8, which is widely thought to be the final season.
Gansa acknowledged that bringing a wild ride like "Homeland" to a conclusion will be no easy task.
"One of the funny things is we have put Claire Danes the actress through so much stuff. It's just amazing the material we've thrown at her and how she's just delivered beyond our wildest expectations every single time, and we have to honor that," he said. "I don't know where it's going end but wherever it ends, it has to honor what's come before it, and that's going to be a challenge.
"Homeland" premieres January 15. The premiere is available in advance for Showtime subscribers.