WASHINGTON — J. David Kuo, an evangelical Christian who was a leader in President George W. Bush’s faith initiative but who later became a critic of it, died on Friday. He was 44.

Mr. Kuo’s wife, Kimberly, said the cause was brain cancer, which was diagnosed 10 years ago.

As deputy director of Mr. Bush’s Office of Faith-Based and Community Initiatives, Mr. Kuo helped implement Mr. Bush’s promise to link the nation’s religious groups with the delivery of social services.

Campaigning for the Republican presidential nomination in 1999, Mr. Bush promised to invigorate “a civil society,” telling The Washington Post that he would encourage churches and charities to be “little armies of compassion.” The faith-based office was a result of that promise.

But Mr. Kuo left the administration after two years, frustrated and disillusioned. He later wrote that the faith office did not receive the billions of dollars that Mr. Bush had pledged. He said the White House had used the office as a political prop.