January 16, 2009  -- McKay Hatch was on a mission. Bothered, he says, by the foul language he heard around school, he formed what he called the No Cussing Club (http://www.nocussing.com), and soon had thousands of followers from around the world.

But then, on the Sunday after New Year's, his father checked the group's e-mail after church and found 7,500 unread messages -- some of them threatening, almost all of them filled with obscenities.

McKay, a 15-year-old high school student from South Pasadena, Calif., has found himself the victim of a massive online attack, with people sending offensive e-mails and trying to crash the group's Web site. Strangers ordered pizzas sent anonymously to the family home in the middle of the night. The Hatches found their mail box clogged with porn magazines.

All, says McKay, because he was trying to make the world a better place.

"A lot of kids at my school, and some of my friends, would cuss and use dirty language all the time," he says. "They did it so much, they didn't even realize they were doing it. It bothered me so much that one day I challenged them to stop."

The No Cussing Club grew from a school project to a national phenomenon. McKay appeared on dozens of news programs, was cited by Dr. Phil, and went to other schools to give inspirational talks.

But then came messages such as this:

"i am going to find you And mutilate you with a scalple" [sic]

Or this:

"Every time I see your stupid [expletive] braces on those stupid [expletive] teeth of yours on that stupid [expletive] face of yours I just want to kill you with my bear fists." [sic]

Another message said, "Now, please, pack up your [expletive], and leave. You all are nothing more than [expletive], and should be treated nothing more than such."

McKay says he can imagine he touched a raw nerve.

"A lot of people were saying I was taking away their freedom of speech," he told ABC News by phone when he came home from school for lunch. "All I was trying to do was raise awareness."

McKay's father, Brent Hatch, says his son has been brave -- but in one day he received 35,000 pieces of spam.

"On the outside, he seems to be doing fine," Mr. Hatch told ABC News, "but last night he came home from soccer practice, and for the first time he started crying. We went out to grab a bite, just to get him out of the house."

McKay said, "At first it was kind of scary, but then I realized they're just bullies, and they wanted me to be scared."

McKay's parents have encouraged him in his quest. They themselves published a book a few years ago, "Raising a G-Rated Family in an X-Rated World." But they say they never expected their son to have to endure more than a few taunts.

"I always give him the option to stop," Brent Hatch said, "but he says, 'No, this is my mission.'"

The Hatches say they called the local police for help, and then the FBI, after death threats turned up on the home answering machine. (The FBI says, as a matter of policy, that it does not confirm or deny whether it is working on a case.) A Los Angeles law firm has offered help too, threatening to sue the Internet service providers whose systems have been used to attack McKay's effort.

Amid all the abusive messages, there have been encouraging ones as well.

"I just want to tell you that I think you are an amazing kid!!" wrote a woman from Canada. "It's a great thing you are doing here. And I am also going to try to cut out my cussing also. Thank you for that!!"

Another person wrote, "You are our future and it is up to you to determine the course of our nation with good morals, values and standards. Thank you for standing up for what you believe in. Keep up the good work!"

Brent Hatch says he's grateful how friends and schoolmates have come to his son's support.

"Good is coming out of it, trust me," he said, "though it's sometimes hard to believe it when something like this happens."