Michael Schwartz, longtime chief of staff to Sen. Tom Coburn and a devout Catholic who was passionate in his crusade against abortion, died Sunday after succumbing to Lou Gehrig’s disease. He was 63.

Schwartz served as Coburn’s chief of staff for almost the entirety of the Oklahoma Republican’s career in the House and Senate, before stepping down in November after his disease made it too difficult to carry out the job’s daily tasks.

“In a place preoccupied by titles and position and power, Mike was an extraordinary servant and faithful leader,” Coburn said in a statement announcing Schwartz’s death. “He showed everyone — by his life, deeds and words — that things that are unseen are the things that matter. As he battled ALS — Lou Gehrig’s disease — he showed us what it means to run the race and finish it strongly. Well done, good and faithful servant.”

For much of his professional life, Schwartz led a fight against abortion that was guided by his Catholic faith, working as a lobbyist with Concerned Women for America and the House Family Caucus before joining Coburn’s staff.

Just days before his death, he received the National Pro-Life Religious Council’s Pro-Life Recognition Award at the National Memorial for the Preborn and their Mothers and Fathers.

In an announcement of Schwartz’s death, the organization Faith & Law — a nonprofit that seeks to help congressional staff understand Christianity — praised Schwartz’s work on Capitol Hill.

“Mike fought valiantly for the unborn from the advent of legalized abortion in America,” the statement reads. “He was an avid reader of the most rigorous books and essays, reading a book or two each week. He relished discussions about God, the Supreme Court, and politics. He was a friend of the high and mighty and the lowly and powerless alike.”

When Schwartz decided to step down from his daily duties on Capitol Hill in November, Coburn delivered an emotional tribute to Schwartz on the Senate floor, praising Schwartz’s courage and selflessness in the way he lead his daily life, always thinking about others before himself, even as his debilitating disease progressed.

“He is one of the kindest, gentlest people anyone has ever met,” Coburn said in the tribute. “He has been a light focused on how we do things to honor other people.”

“He is still the guy who cares more about other people than himself,” Coburn continued. “The kindness he has shown to everyone he has encountered, whether to a homeless person on the street or a leading senator in the halls, he has reminded our team and me that we are all equal regardless of position in the eyes of God.”

A public funeral for Schwartz will be held at 1:30 p.m. on Thursday at the Mother Seton Parish in Germantown, Md.