Christopher Knight on Working with 'Brady Bunch' Costars on New Christmas Movie: We're 'Like Family'

Christopher Knight can't seem to escape his past as Peter Brady on The Brady Bunch — and he doesn't mind one bit.

The 64-year-old actor has played many roles, both on- and off-screen, since starring as the impulsive middle son on the hit 1970s sitcom, and his latest gig finds him back in the spotlight with his TV family. Five of his former castmates — Barry Williams (who played Greg Brady), Mike Lookinland (Bobby), Susan Olsen (Cindy) and Robbie Rist (cousin Oliver) — join him in People Presents: Blending Christmas, a Lifetime Christmas movie that also stars Haylie Duff and Aaron O'Connell.

"It didn't feel like work," Knight tells PEOPLE of the heartwarming film (premiering December 12), which was shot in Simi Valley, California, not far from Hermosa Beach, where he lives with his wife of five years, Cara Kokenes. "I say yes to projects that we're all in not just because of the project, but because it's an opportunity to catch up and have fun again. Every time we get together, it's like no time has passed."

He adds with a laugh: "We're like a family who live in different states and get together around the holidays."

The project was the first for many of the stars amid the COVID-19 pandemic, Knight says, and being able to spend time with friends he's known for over 50 years was a treat after months of isolation.

"I was shocked that we were actually going to work, because that wasn't something that had been done by me through that entire first year of the pandemic. I hadn't traveled anywhere," he says. "So this was me removing the envelope, if you will, and what a perfect group to do it with."

The movie seemed like a natural fit for the former Bradys, Knight says, because its plot — two families coming together at the holidays as the protagonists get engaged — is similar to that of the show that made them famous.

"The movie tells the story of these families learning to get along, which is something that seems like, in every Brady episode, we had to be reminded of," he says. Plus, "In the same way that Christmas is evergreen, the Bradys are evergreen. They're like a comfortable old pair of sweats."

Knight says that he's been told by many people that they began watching the show again during the pandemic because of the sense of comfort it brought them.

"I heard more so last year than previous years how much [adults] found The Brady Bunch," he says. "They put some sweats on and crawled up onto their couch under their comfy blanket and watched a number of episodes, because it was comforting. It was known. It was sweet. It wasn't chaotic… It gives people some hope that maybe we can get back to that."

Being a constant source of joy and familiarity in people's lives wasn't something Knight or any of his castmates ever considered when they were filming The Brady Bunch, he says. But now, it's one of the greatest honors of his life.

"The show was entertainment, but it actually transcended its initial purpose. It's become an icon of sorts, a touchstone, a representative of what maybe the quintessential American family ought to be," he says. "And as often as somebody was watching us because we paralleled their lives, somebody was watching us because they were an only child, and then we became their brothers and sisters. And I fully respect that and enjoy it."

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And as much as the cast enjoys coming together to do new projects — they recently linked up for HGTV's A Very Brady Renovation in 2019 — it's extra special for them because their fans seem just as excited about their reunions as they are.

"I think it's comforting for people that we do get along, that we do treat each other as friends," he says, adding that it's been "a privilege" to continue to do follow-up projects with them, because it means they have been able to keep up their friendship over the years.

"I have known them for nearly as long as I've known my own kin, and no one longer," he says. "This Brady thing, which happens to be as alive today as it was 50 years ago, hasn't allowed us to be apart. That makes us family, and that's the common ingredient."

PEOPLE Presents: Blending Christmas, which is directed by Marla Sokoloff, premieres Dec. 12 at 8 p.m. ET/PT on Lifetime.