The anonymous writer warned their invitations had been forwarded on to an anti-gay group in the Canton Akron area, saying protests would be taking place.
"This day is going to be ruined for you. This is going to be a fun show to watch. You both are going to get what you deserve."
When he first read it, Keith said he thought the letter had to be a joke.
"It just doesn't sound real," he told Fox.
"We thought we knew the people that were coming, and I guess we didn't know all that well."
The pair has been together for nine years. They poured their hearts into the wedding, painting decorations, gifts and even building their own cake stand.
But on the plus side, Keith said they never had one thought of cancelling their special day.
"Other than our initial shock of the letter, this made us both want to do it more.
"Love will win in the end. That's what it comes down to."
History has already shown that these anti-gay protests tend not to work too well.
Just last Saturday night in Melbourne, when 600 young LGBT students celebrated the Same Sex & Gender Diverse Formal at St Kilda Town Hall, they had 30 volunteers dressed as angels to stop any potential protesters from disrupting the event.
The idea was inspired by Matthew Shepard's Angels, who similarly dressed up when the Westboro Baptist Church attempted to protest the trials of the men who murdered Matthew. They wore huge, outstretched wings to block negative signs from view.
Keith and Chad's wedding will be on private property regardless, so they say those opposed to it definitely won't be getting in.
But hey, if the protesters are too cowardly to add their own names to a letter they've written, it's safe to assume they won't show their faces either.
- news.com.au