The man accused of shooting a security guard inside the Family Research Council headquarters now faces a terrorism charge.
Floyd Lee Corkins is the first person in 10 years to be prosecuted under the District of Columbia's Anti-Terrorism Act of 2002.
Police arrested Corkins in August. He is accused of opening fire inside the lobby of the FRC's downtown Washington building.
Corkins reportedly announced, "I don't like your politics," as he shot guard Leonardo Johnson.
Though wounded, Johnson still managed to help take down the gunman before anyone else was injured or killed.
Investigators say Corkins was carrying a backpack with ammunition and Chick-fil-a sandwiches. The incident happened after Chick-fil-a's president made headlines by standing up for traditional marriage.
Corkins' parents have said he strongly supports gay rights.
"The terrorism indictment announced today ... makes clear that acts of violence designed to intimidate and silence those who support natural marriage and traditional morality violate the law and undermine the security and stability of our form of government," FRC President Tony Perkins said in statement Wednesday.
Perkins said those who label his organization a hate group share some of the blame.
"We again call on organizations like the Southern Poverty Law Center to stop its reckless practice of labeling organizations that oppose their promotion of homosexuality," Perkins continued.
"The SPLC's 'hate' labeling of Christian organizations is fostering a dangerous and deadly environment of hostility and it needs to stop," he said.
After the shooting, Andrea Lafferty, president of the Traditional Values Coalition, revealed that she was told by authorities that a note containing her group's contact information was found in Corkins' pocket.