"Stop asking for money, let the baby die, it's called Darwinism, Happy Holidays."
Ahlers had set up flyers near a mall in Toledo, Ohio, to raise money for his little boy Randy James, affectionately known as RJ. But when he drove around the area last week, he noticed that someone had answered with a hateful message.
Although they have health insurance, the bills add up. A test ordered by a geneticist cost $ 10,000.
So Ahlers and his wife were looking for donations.
He just could not believe that someone reading his mark could have so little empathy.
"It shocked me," he told WTVG. "I mean, it really shocked me that someone would have that kind of cruelty."
Despite the hurtful message, most of the community has worked for them. Angela Ahlers, RJ's mother, told CNN that they had received an outpouring of love and support from people in Australia, Argentina and Canada.
"This sign was just the opposite of what this person wanted because it has obviously become global," she said.
On Tuesday afternoon, GoFundMe had raised more than $ 33,000 toward RJ's $ 20,000 target.  For the time being the couple says that they take the highway.
"We want to raise our son to not return hatred with hatred, we want to fight hatred with love," said KC Ahlers to WTVG. "Well, we obviously know that someone who did this is disturbed, and we hope he gets help, but we will continue to pick up your marks when we see them, because this city does not need hate Love."