How do you combat willful ignorance?

Fritz is gay and has an identical twin, Frank, who is straight. Both were heavily involved in trying to prevent the Calif. marriage ban. Frank had to stay home one day so his landlord could send over a handyman to fix a leaky sink. The handyman brought his wife along and Frank ended up talking to the two about all kinds of things.

Then the wife saw the "No on Prop 8" magnet on the refrigerator and commented that she and her husband were Mormon and, of course, voted for it. Yikes! Since Frank wasn't paying the bill (the landlord was) he took the opportunity to calmly find out why they voted the way they did.

He found they are a very nice couple, willing to go to great lengths to help out those in need. However, they have no concept of separation of church and state. My guess it isn't because the church controls the government in Utah, but because the church is the government that matters. They didn't seem to understand (or care) how the secular government worked. They voted for the ban to protect their own religious views of marriage (and Mormonism is very tied up with marriage, which for them extends into heaven and is a requirement for getting into the best parts of heaven). The idea that the ban would harm other people didn't enter the discussion. Gays were not mentioned. Thus they were quite surprised at the protests. They don't hate anyone, though that might be described as not having feelings of animosity or anger towards gays. They felt unjustly accused.

By the time the leak was fixed Frank had concluded they were willfully ignorant of anything not approved by their church. That left Frank wondering. How do you combat willful ignorance?

A commenter to this post put it this way:
They don't know.
They don't want to know.
You can't make them know.