WASHINGTON, D.C. — Frank Siller still goes to the same Catholic church he has gone to since he was a little kid, Blessed Sacrament in the New York City borough of Staten Island. He always sits in his family’s same pew for Mass.

This is one illustration of the strong place the Catholic faith has in the lives of Siller, 68, and his siblings as they do the work of the Tunnel to Towers Foundation.

They began the foundation to honor the sacrifice of Stephen, their baby brother, a firefighter with the Fire Department of the City of New York who gave his life, like so many others did, trying to save lives on 9/11 — the worst terrorist attack on U.S. soil.

The foundation helps the spouses and children of firefighters and police officers killed in the line of duty, and for many of these families pays off their remaining mortgage. Its Gold Star program provides mortgage-free homes to Gold Star families with young children of military members who have died while serving their country.

It also assists military members who return home from war with catastrophic injuries by providing these warriors and their families new mortgage-free, specially adapted smart homes — 100 and counting. And it plans to build a community of these mortgage-free smart homes called “Let Us Do Good Village” in Florida.

“Catholic faith drives all we do,” said Siller, the foundation’s CEO and chairman.

His late parents, George and Mae, were secular Franciscans who taught their seven children to follow the example of St. Francis of Assisi, who made Christ the center of his life in serving others. The elder Sillers always quoted one of the saint’s well-known sayings: “While we have time, let us do good.”

“It’s a simple mission,” Siller said of the foundation’s work. “But it is very important we succeed and take care of the families left behind.”

He spoke to Catholic News Service ahead of his “Never Forget Walk,” a more than 500-mile journey through six states to mark the 20th anniversary of the terrorist attacks, taking him from the Pentagon in Virginia to Shanksville, Pennsylvania, and then to New York City and “ground zero” in lower Manhattan, the former site of the World Trade Center. Siller expects to complete the walk by Sept. 11.

“It is first time I’ve done anything like this — 525 miles,” he said. “I decided to do it because I wanted to make sure we shine a big light on what happened 20 years ago. It’s meaningful and personal for the foundation to go to the three locations that had such great loss of life.”

The morning of Sept. 11, 2001, terrorists hijacked two passenger planes and flew them into the World Trade Center, destroying the twin towers.

This attack was quickly followed by terrorists flying a third hijacked passenger plane into the Pentagon. A fourth passenger plane, initially headed to Washington, crashed into a field near Shanksville after passengers thwarted the hijackers.

Nearly 3,000 people were killed in the attacks, including the 246 passengers and 19 hijackers aboard the planes. Over 6,000 others were injured, and many people have suffered substantial long-term health consequences.

It is one of the single deadliest terrorist attacks in human history and is the single deadliest incident for firefighters and law enforcement officers in the history of the United States, with 343 and 72 killed, respectively.

The “Never Forget Walk” is really “becoming more of a spiritual journey,” said Siller, who is being joined along the way by families the foundation has helped as well first responders, military members, veterans and supporters of the foundation.

On Aug. 1, he and his family held a private wreath-laying ceremony at the Pentagon in Virginia, then joined the other participants to begin the walk at nearby Arlington County Fire Station 5, one of the stations that responded to the 9/11 attack on the Pentagon.

Siller said he and his siblings didn’t set out to do all that the foundation is doing now but the effort has grown. The enterprise began as a way to “honor our brother’s sacrifice,” he said. “There is no greater love than what he gave — his life for strangers. … We were just moved, inspired by his selflessness.”

“We’re a very simple blue collar family,” he said. “There is no doubt that God has put us in a position to do this work. None of us get paid, we’re volunteers.”

The “foundation of the foundation is the family,” said Msgr. Peter G. Finn, former pastor of Staten Island’s Blessed Sacrament Parish.

The Sillers “are devoted to each other. They are a very dedicated group of people, faithful to religion, family and community,” the retired priest told CNS. “Frank exemplifies it. … What he’s doing now is an ongoing thing he’s been doing for most of his life.”

Before Stephen’s tragic death and the foundation that followed, he said, people already knew Frank for his charitable efforts “and his kindness.” He “has a supporting cast of family that are unbelievable in their goodness and faith and their kindness,” added Finn, a former director of communications for the New York Archdiocese and a former seminary rector.

Frank Siller’s commitment to the foundation is “almost apostolic,” the priest said. “He’s a tough guy, a good guy and he’d work himself down to the bone to make sure this (effort) continues.”

The foundation gets its funding from “the masses,” Siller noted, adding with a laugh, “I don’t say that because of Catholic Masses.” Grassroots donors who commit $11 a month support the foundation, not corporate donors.

“Everybody should do something for our military that die for us, the cops and firemen,” he said. Those who give $11 a month see what the foundation does and can say “my $11 a month did that,” he added.

The “Tunnel” in the foundation’s name is the Brooklyn Battery Tunnel. Stephen Siller, 34, ran through the two-mile tunnel to the site of the World Trade Center. He was off duty that day but heard the emergency calls, and suited up and carried his 60 pounds of FDNY gear on his back through the tunnel. He left behind his wife, Sarah, and their five children.

His brother running through the tunnel that day also serves as a metaphor for how the Siller family eventually worked through the grief his death brought — they moved through the “tunnel of despair to find hope” and turned tragedy into service, and they work to help others through the same tunnel.

“Everything we do is focused on doing good,” Siller said, and helping those who “lose loved ones with no notice (and) have to continue living with this unbelievable sadness and try to bring joy into their life.”

“You can survive it,” Siller said. “Mae and George wouldn’t let us complain about a thing,” and would always tell their children to “do something for someone else.”

He said he told his own children the same thing when they were growing up. He has three children and six grandchildren.

Siller misses Stephen every day. They were the closest in age of all their siblings, and he had a role in helping raise his little brother.

By the time, Stephen was 10, their mom and dad had died. The oldest Siller, Russ, and Russ’s wife, Jacky, took in Stephen and raised him with the help of Frank and the others. Russ died Nov. 8, 2019 at age 77.

The first thing Siller does every morning is look at his photos of Stephen, Russ, and his mom and dad, and tells them, “Good morning.”

Family, faith, God and ” most certainly our country” are top of mind for him every day, he said.

And his mission has been the same since 9/11: Never forget.