Marine Challenges ISIS on Social Media

— -- Support is mounting for a Medal of Honor recipient who is threatening terrorists on Twitter after the FBI warned soldiers to lie low on social media.

Dakota Meyer, who served in the Marines for four years, is trying to make the point that he doesn't want to live in fear because of ISIS, he told ABC News today.

He even challenged the terrorists to show up at his door.

"When I start having to change my life because I'm worried about something that could happen to me, that means terrorism is winning," he said. "That means terrorism is working.

"I refuse to let these idealistic, radical bullies change the way that I live," Meyer, 26, added.

The FBI issued a warning Sunday to urge members of the military to review their social media accounts for anything that might attract unwanted attention from "violent extremists," or reveal their identities to ISIS and supporters.

"I'm just tired of the warnings," said Meyer, whose outspoken comments on Facebook and Twitter have gone viral since he responded to the FBI warning. "Maybe the FBI should give [the terrorists] the warnings."

He even tweeted a photo of himself reading a Marines handbook and invited ISIS members to his "book club."

Meyer, who lives in Kentucky, was awarded the Medal of Honor in 2011. He stressed that he does not wish harm upon any fellow members of the military.

"I'm not saying I want ISIS to go attack the military," he said. "I'm speaking on behalf of myself.

"I just want us, as Americans, to stop living in fear and stop worrying about what they're going to do. I want us to stand up against these people."

He called ISIS "cowards" in a viral Facebook post and urged supporters to post photos of U.S. flags on his page. The post got nearly 8,000 "likes" in two hours.

"I'm definitely not scared of them," he said today. "And I can't think of a better purpose to serve than standing up against those who are trying to instill fear in Americans."

Meyer battled accusations in 2011 that he was mentally unstable and overstated his actions in Afghanistan, but the White House later said it stands by giving Meyer the Medal of Honor for his "extraordinary service."

He has been hailed a hero for entering a kill zone during a 2009 ambush in Kunar Province, Afghanistan, to search for missing troops, and then carrying out four bodies of friends who had been killed in the attack.