There are 3 main types of Furry Haters, with 1 thats not actually a hater at all, but instead takes advantage of an already battered and assaulted fandom:
Some Haters are driven by church beliefs about "furries" being horrible blasphemy against gods creatures, in other words they hate that they are fusing animals together and destroying the way they are meant to be.
Some haters are driven by pure moral values and species patriotism, saying that what they have done to the human species, or what they have given animals from the human species, is horribly insulting and they should be ashamed of themselves as human. Sometimes even saying that calling a furry fandom member “human” is insulting.
Then there is the smartest of the haters who say the love of anthropomorphic characters and ideas could lead people into trying genetically modify human and animal DNA trying to make anthropomorphic ideas come true, which would inevitably fail.
Though there are some people who actually just don't understand the furry culture, they are just "Wannabe Trolls" taking advantage of the tattered Furry Fandom.
The generic comeback of furries is to say "You don't understand the furry culture" is just as accurate as saying "Lawyers never wear suits". Clearly inaccurate.
10% of the people are actually furry haters who fully understand furries and have legitimate reasons to hate.
People hate on furries because they don't know any better. People repeat all sorts of hateful B.S. about furries without questioning it, and that's sad.
What people say about furries says more about them than it does about furries.
These people usually have never even attempted to understand the furry culture, nor have ever considered just shutting up and letting the furries do their thing and doing their own thing themselves.
Furry Haters are frequently seen in furry focused forums and chatrooms, there only to troll.
B: Hi room! :3
B: Hey there B *glomps, tail wagging
A: *pushes the stupid furfag off him and shoots him in the balls
B: wtf, what's wrong with you?
A: stfu you stupid faggot, you don't deserve to live.
People whose view on the 'furry fandom' drastically conflict with those in the 'furry fandom', and often results in 'trolling'; abusive, aggressive, or otherwise antagonistic behaviour, described as such due to the responses of those in the fandom - aka "Furries" - who take the actions and opinions of 'furry haters' as personal attacks. In many cases (YouTube is a good place to support this claim), 'haters' (broadly concatenated) will claim hatred for those in the 'fandom', and will proceed to virtually disapprove of everything and everyone involved or related to the 'fandom'.
Some rumours surrounding the reasons behind 'furry haters' is the belief that 'Furries' commit bestiality. While there is no solid evidence of this, it cannot be ruled out, simply due to probability and human diversity. It may be coincidental that a 'Furry' in the 'fandom' may commit beastiality, but again no proof exists.
Ethically, 'haters' may choose to 'hate on' (to commit acts of hatred against) 'Furries' due to the particular 'Fur's'/'Furry's' sexuality. This is rather a combination of perspectives, in so far as a dislike for 'Furries' as a whole, combined with a dislike for homosexuals/bisexuals.
Often, 'furry haters' will exercise defamation of character, an offence in the United Kingdom, and can be legally defended if the right advice has been sought.
"Yiff In Hell Furfags!"