For fans of Amy Grant and Michael W. Smith, the notion of the two of them sharing a stage is nirvana.

Last summer, the Christian-pop behemoths – tight comrades and collaborators throughout the ‘80s and early ‘90s -- were reunited for a one-off show in Detroit and the flood of memories that hit them both was enough to jump-start a tour.

Earlier this year, Smith and the Augusta-born Grant, who is the biggest-selling artist in contemporary Christian music history with 30 million albums moved, embarked on the “2 Friends” tour, their first extensive live pairing in 20 years.

The name of the excursion, which comes to Chastain Park Amphitheatre on Friday, is both a nod to their 1983 collaboration, the tender ballad “Friends,” and their own enduring connection.

“It’s so comfortable. It’s nice to have relationships that last a long time. It’s like doing a show with family,” Grant said last week from her home in Nashville.

Smith (aka “Smitty”) and Grant initially bonded in the early ‘80s, when Smith toured as Grant’s keyboardist on her “Age to Age” outing. Throughout the years, their names were always professionally linked, with Smith co-writing several of Grant’s best-known songs (“Thy Word,” “Find a Way,” “Lead Me On”) and touring with her on the 1988 “Lead Me On” world tour.

In the early ‘90s, both of their careers exploded into the mainstream. Grant flirted with pop stardom after her five-times-platinum “Heart in Motion” album spawned the ubiquitous radio hits “Baby Baby,” “Every Heartbeat” and “That’s What Love is For,” while Smith’s ballad “Place in This World” commandeered adult contemporary radio.

The pair recorded a soaring duet on Smith’s “Change Your World” album called “Somewhere, Somehow” that had never been performed live until this “2 Friends” tour. Expect to hear it Friday.

The show, which includes more than 30 songs from the two artists, opens with both performing Grant’s wintry nostalgic ode, “Stay for Awhile,” and other songs. Grant handles the majority of the first set solo and after an intermission, Smith launches the second half of the show. Duets are sprinkled throughout.

Grant said her favorite portion of the concert is the “unstructured time around the piano.”

And among her favorites to perform? “Probably ‘Lead Me On’ and ‘Emmanuel.’ I hadn’t done that one in forever and I love the arrangement,” she said.

Grant is just back from a short tour of the United Kingdom – her first appearance there in 16 years – and will remain on the road most of the year. The “2 Friends” tour will segue into her annual Christmas romp with husband Vince Gill.

“I’m touring more this year than I have in a decade. It’s just been really enjoyable and I think maybe turning 50 [last November] really made me grateful for the chance to still do something I love,” Grant said, then added with a laugh, “Also, being down to one child at home helps, a child who I guess we’ll be dragging on the road.”

She’s referring to 10-year-old Corinna, her daughter with Gill. Her other three children with first husband Gary Chapman – Matt, Millie and Sarah -- are now college-aged adults.

After this season’s Christmas tour, which is expected to land at the Fox Theatre Dec. 19 as well as in Augusta and Savannah, Grant plans to hunker down in the studio from January until April to write and record a new album.

As for the musical direction, she isn’t quite sure yet if the record will go more of a pop route or a traditional one.

“I’d just say at this point it’s going the song route. I love songs that tell a story,” she said.

And fans will hear plenty of those this week.

Concert preview

Amy Grant and Michael W. Smith

8 p.m. July 29. $25-$65. Chastain Park Amphitheatre, 4469 Stella Drive, Atlanta. 1-800-745-3000, www.ticketmaster.com.