The criminalization of Holocaust denial will not protect Israel. It is not possible to make someone believe something happened by criminalization of the belief it didn't happen. It is not possible to make people respect the right of Israel to exist when they have been informed it does not by their own belief system. There will be no tolerance or pity from the people who feel the existence of Israel is an affront to their own identity.
Denial of the Holocaust is an abhorrent statement based o repulsive thinking; however, it is not appropriate to criminalize someone for believing or stating something ignorant. Educating people about the facts of history is the best defense against such behavior, but making someone a criminal for denying history is not the way to change people's minds. If anything. it will make them see the world as even more against them and make them endorse their wrong opinion even more.