I knew I was in trouble as soon as I pulled into the parking lot of the Quality Inn in Americus, Ga., last Saturday night. It was long past dark but I could see well enough to note the out-of-state license plates — New Mexico, Pennsylvania, California, Alaska — places far from this peanut-farming land.

We were all there for the same reason: to see Jimmy Carter teach Sunday school at the Maranatha Baptist Church in the nearby town of Plains. And if the crowded parking lot was any indication, finding a seat the next morning would be a challenge.

After the inauguration of Ronald Reagan in 1981, President Carter returned to Plains, his hometown. Throughout the longest and most influential post-presidencyin American history, he has continued teaching Sunday school, and the public is always welcome to sit in.

President Carter’s commitment to human rights — executed largely though Habitat for Humanity and The Carter Center, which works to eradicate poverty and disease and cultivate democracy — earned him a Nobel Peace Prize in 2002. In his acceptance address, President Carter said, “God gives us the capacity for choice. We can choose to alleviate suffering. We can choose to work together for peace.” Even when he isn’t teaching Sunday school, his unwavering Christian faith informs everything he says and does.

My own faith in religious and democratic institutions has not been so unwavering, especially not since white Christians put a demagogue in the White House. But I have always wanted to go to his Sunday school class. When President Carter, now 93, announced that he was cutting back on his teaching schedule at the church and publishing a new book — “Faith: A Journey for All” — it seemed almost like a sign. Jimmy Carter still has faith in this country, and I hoped his Sunday school lesson might restore my faith, too.

The sanctuary of the Maranatha Baptist Church seats 350 people, and there’s a spillover room with a live video feed for another 100 or so. “Based on recent attendance trends, visitors who arrived before 6 a.m. had no problem obtaining a sanctuary seat,” the church’s website reads.

In my motel room I set the alarm for an hour I haven’t seen since 1998, the last time there was a newborn baby in my house. Fifteen minutes before it went off, I heard the pipes rattling as someone in the next room took a shower, so I jumped in the shower myself. Trying to beat a total stranger to Sunday school is not exactly in the spirit of Christian charity, but I wanted a seat in that sanctuary.

In springtime, rural Southwest Georgia is as pretty a place as you will find on this earth — wildflowers swathing the fallow fields and blooming along the edges of red soil already plowed for planting, bluebirds hunting from fence posts, mockingbirds sending dueling songs into the pines — but I couldn’t see any of that from Highway 280 in the predawn darkness.

I arrived at the church and was given a number — 41 — and told to park in the pecan orchard because the lot was already full. At 7:45 it would be time to get in line to be checked by the Secret Service. I wasn’t there early enough to be guaranteed a seat in the sanctuary, a church member said, but it wasn’t out of the realm of possibility.

Thanks to the early riser in the motel room next door, I made it into the sanctuary. While we waited for President Carter to arrive, I chatted with a Baptist minister sitting in the pew behind me about a recent interview with Stephen Colbert, in which Mr. Carter hinted that he considers the sitting president of the United States a liar. Asked what it takes to be president, he told Mr. Colbert, “I used to think it was to tell the truth. But I’ve changed my mind lately.”

There were flashes of the same impish wit on display at the church in Plains. “Do we have any visitors this morning?” he joked to the crowd. He asked where we were all from, and voices sang out from places like Cameroon, Israel, Uzbekistan.

When it was time for the lesson itself, President Carter stood smiling and spoke without referring to notes, moving to the lectern only to read from the scripture. The text was from the Acts of the Apostles, passages concerning the priorities of the early church. “They worshiped together. They had fellowship together. And a third thing: They took care of each other’s needs, even in a sacrificial way,” he said. He spoke particularly about the generosity of Barnabas, who sold his own field and gave the money to Jesus’ apostles to distribute to the needy.

President Carter is not a pacing, gesturing, booming-voiced orator, but he is a brilliant teacher — moving nimbly between his memories, his concerns for the world and what the Acts have to say about the right relationship of human beings to one another. He asks questions, nods encouragement when an answer is close but keeps nudging until someone hits on the point he’s trying to make.

“We have lost faith in a lot of things that have always nurtured us,” he said. “Many people in the world have lost faith in democracy. We’ve lost faith in the sanctity of telling the truth and the value of education. We’ve lost faith in the equality of people. In our country’s history, some of our greatest struggles have been over the issue of equality.”

Then he asked the congregation what year women in the United States gained the right to vote.

Several called out “1920!” But it was a trick question. “That was white women,” he reminded us. “A lot of white people don’t remember that distinction.”

He spoke movingly about his first security briefing as president-elect, about the solemn responsibility of the country’s commander in chief to safeguard nuclear weapons. “If we don’t figure out as collective human beings how to get along with each other, even the people we don’t like and with whom we don’t agree — say the Americans and the Russians, the Americans and the Chinese, the Americans and anybody else — if we don’t figure out collectively how to get along with each other and take care of each other, that might be the end of humanity.”

President Carter is a realist, and he’s concerned about the current state of the world, but he was also careful to say he doesn’t believe the worst will happen — “I’m a Christian, and I believe God’s will and God’s love will prevail, but I worry about it.” And he returned again to his call to “take care of each other, even the people that we don’t like, even our enemies.” At the Maranatha Baptist Church, a Sunday school lesson is a master class in responsibility and goodness and, above all, love.

He reminded the congregation that Barnabas was known among the early Christians as “the encourager.” And encouragement is clearly something Jimmy Carter knows a great deal about.