The point you seem to be wilfully ignoring is that the electorate voted for them. Voted. In a democratic fashion. Neither you or I may like it, but Jobbik gained over 20% of the Hungarian vote, so if that proportion of the population want them to represent them, who are you to say they can't. In...
Juvenile nonsense. The whole of Europe has PR in one form or another. Remind me when, in the past 70 years has an extremist party swept to power in Germany. Or Switzerland. or Denmark. Or Sweden. Or Norway. Or the Netherlands.
Get a better argument.
FPTP encourages tactical voting, as well as protest voting. If people felt their vote was worth something, they would change their behaviour and vote for the party they truly wanted.