I think something like this should be relevant. Social pressure is a good way to encourage someone to discard outdated beliefs like this.
If he had donated $1000 to a fund opposing inter-racial marriage, or to a fund opposing voting rights for a class of citizens, would you still feel the same way?
If he had donated $1000 to a fund opposing inter-racial marriage, or to a fund opposing voting rights for a class of citizens, would you still feel the same way?