On July 23 this year, Bernice Underwood will turn 100, joining her two best friends—Gladys Butler and Ruth Hammett—as centenarians. A fourth friend, Leona Barnes, would have turned 100, too, this July, but she passed away last May.

Remarkably, they have been the best of friends for almost their entire lives—for 94 years!

The four grew up in Washington, D.C. in the early 1900s at a time when there were horses and wagons, instead of cars, on the streets, according to Butler.

The four really old friends were featured in a CBN News special earlier this year. The video clip of their interview on the CBN News Facebook page got more than 13 million views with comments coming from all corners of the world!

The video also led to interviews with other national news outlets, book offers and speaking engagements.

In all those interviews, questions inevitably cropped up on how they manage to live this long, how they maintain their zest for life, and what has been keeping their friendship intact through all these years.

To all these questions, the three have one answer: Their faith in God.

"That's the way we live and her parents and all of our parents were friends. Church people. Church-going people, and that kept us united together," said Barnes.

"All of our parents were friends, church-going people," she said. "And that kept us united together.... We had neighbours that looked out for one another. If you were sick, they would reach across the fence and give you soup."

Underwood, Butler and Hammett attended Mt. Zion Baptist Church as children. Barnes joined them in the evenings after homework and chores.

The video shows the four women sitting on a pew at Mt. Zion, laughing and smiling as they reminisce the past.

"I am thankful... to get to the age that I am," said Butler.

When asked what's their secret, Butler said there is none.

"It's only by the grace of God that we're here, and I praise Him every day and thank Him every day for being here because He's the only one keeping me."

Barnes agreed.

"Honey, ain't nothing like faith in God... You have to have faith in God. I'm sorry for preaching. I just have to tell it," she said.

Hammett is suffering from early-onset dementia. But when CBN News asked her what her favourite hymn was, she started singing "I Surrender All." As she sang "all to Jesus, blessed saviour, I surrender all," everyone in the room had tears rolling down their cheeks.

The women were honoured, one of them posthumously, at a well-attended celebration at Zion Baptist Church on June 18.

Even though Barnes didn't live long enough to attend the celebration, she told CBN News earlier that she would enjoy every single moment of life until God called her home.

"It's just a blessing from God that we're here and we take each day as it comes, and I do. Each day that I wake up in the morning I say 'Thank you. Jesus. This is just one more day that You've given me that You didn't have to,'" Barnes said.