Fear that they may be romantically pursued by them.
Fear they may pursue someone they assumed was straight but isn't.
Fear that the object of their attraction was born their same gender.
Fear their children will grow up viewing LGBT community positively.
Fear their own children may one day announce they are LGBT
Last but not least religious beliefs are used. Although everyone "cherry picks" which scriptures they will observe.
They'll say: "LGBT is a sin!"
So is pre-marital sex, telling lies, stealing, and a whole host of other things they themselves have participated in over and over again.
Just as with racism some people only feel comfortable around people who are just like them. They don't want to accept or tolerate others that are different.
In all honesty I don't believe there are a lot of people who are genuinely "LGBT phobic" especially if we define phobic as "fear".
The reality is some people simply HATE whomever for whatever reason. They're not phobic or "afraid" of them!
The KKK and Skin Heads aren't black or minority phobic.
A misogynist is not a man who is "afraid of women" or has a phobia of them. He simply hates them and believes he's better than them.
Whenever the LGBT community seeks (equality) with heterosexuals they are accused of pushing a "gay agenda".
Equality is not an agenda it's a right . Discrimination is wrong.