“My career is going to college,” Carrie Underwood quipped early on in her Sept. 3 concert before 6,852 fans at the Great Allentown Fair.

Underwood was referring to her 17-year career, dating to when she began and won “American Idol” in 2005.

Underwood is nothing if not modest. By any measure of success in the music business, whether it be record sales, chart-topping hits, awards and critical accolades, Underwood’s career has already garnered a PhD.

In her third appearance as headliner at the Fair’s Grandstand, Underwood put on a phenomenal concert that demonstrated that her years of career “classes” as songwriter, recording artist and concert performer have not only prepared her well for “college,” but given her several honorary degrees.

The 8:15 p.m. start of Underwood’s Fair Grandstand concert rang out with “Church Bells,” followed in quick succession by “Southbound” and “Cowboy Casanova” (third studio album, “Play On,” 2009).

“It’s great to be back. This isn’t my first time here,” she said. Underwood headlined Grandstand concerts in 2007 and 2015 at the Allentown Fair.

Underwood puts her whole body into her performances, leaning forward, crouching, knees bent, as she belts out the big notes. Her animated style was emphasized by a flashy outfit of black knee-high heeled boots, black sequined shorts and gray-black sequined top.

The big notes were frequent and impressive. Her voice is a magnificent instrument that is as powerful as it is subtle. She’s able to navigate the crescendos and the quiet moments of her hit songs, many of which she’s co-written.

She’s not afraid or embarrassed to credit to where she feels the credit is due. “The good Lord has done some awesome things,” she said to a sympathetic and enthusiastic audience. Recalling that she saw Alan Jackson and Faith Hill concerts as a young fan, she said, “I didn’t know how I’d get on the stage.”

On the huge Fairgrounds Grandstand stage, Carrie Underwood was not only as a forceful performer, but a comfortable performer.

When she walked up the center stage steps onto a riser to perform “Choctaw County Affair” (fifth studio album, “Storyteller,” 2015) and found that there was no harmonica, she matter of fact said, “I’m about to perform on the harmonica.” But where was the harmonica? “No pressure,” she joked. A harmonica was soon brought forth, and Underwood proceeded to do a harmonica duo and solo bar none during the song.

Speaking of bars, the big screen in the center of the stage that provided a multiplicity of cinematic and art gallery-like images, displayed a saloon exterior for “Drinking Alone” (sixth studio album, “Cry Pretty,” 2018), a slow bluesy number akin to Peggy Lee’s “Fever,” which included a tremendous saxophone solo.

In the guise of the protagonists in her songs, Underwood gives as good as she gets, and then some.

Many of Underwood’s song lyrics display a strong independent streak, almost one of defiance, or at least of vociferous equality, in the face of toxic masculinity, as for example, “Dirty Laundry,” “All-American Girl” (second album, “Carnival Ride,” 2007) and “Undo It,” each of which can be interpreted as a strong statement of female empowerment.

Underwood’s songs can be deceptively simple yet deeply profound. Underwood married National Hockey League player Mike Fisher in 2010. They have two sons, Isaiah, 6, and Jacob, 2. Between the births of their sons, Underwood had three miscarriages. “Cry Pretty “ (2018) addresses such heartache.

And at the heart of the Allentown Fair concert and Underwood’s recordings (notably, the Christmas album. “My Gift,” 2020, and the gospel album, “My Savior,” 2021) are her evangelical Christian beliefs, exemplified in one of her first big hits, “Jesus Take The Wheel” (debut album, “Some Hearts,” 2005). Instead of raised cups of beer, many in the audience raised an arm, palm out and waving as one might during a praise song at a full-gospel church service.

“See You Again” (fourth studio album, “Blown Away,” 2013) puts forth a belief in the afterlife and meeting loved ones (and others, presumably), who have gone before.

“Sing it if you know it,” she said to introduce another faith-based hit song, “Something In The Water” (compilation album, “Greatest Hits: Decade No, 1,” 2014).

“Love Wins” (from the “Cry Pretty” album) was among the 22 songs in the concert that concluded at 9:52 p.m. The song’s opening lyrics, “A stray bullet and a momma cries/Her baby won’t be coming home tonight” resound from the streets of Allentown to war-torn Afghanistan.

The concert by Carrie Underwood was moving and comforting for many, no more so than for Angelo Scanzello of Catasauqua.

“My mother was supposed to be here. She [Joann] passed away. But she’s here in spirit,” Scanzello said. Attending the concert with him were Michelle Schmall of Whitehall and Monica Pavolko of Coplay.

No doubt, the Allentown Fair concert by Carrie Underwood was moving and comforting for many.