I don't see why it is hard to believe that Hamas sing about killing all Zionists, I'm sure there have been many songs about killing genocidal right-wing fascists in the past, but it is important that they don't say "kill all Israelis" or "kill all Jews".
We must stand up against these fundamentalists who just want to slaughter innocent people, if they run out of Gazans to kill do you think they will stop, of course not because they are deranged homicidal maniacs who think they are normal and justified in their actions because they get support and arms from the West, if we started treating them how we treat all of the other religious fundamentalists in the Middle East I think they might come to their senses a bit quicker, at the moment the USA and Western and Arab govts are giving them the green light to carry on.
It is difficult to know how many Hamas would continue with their violent activities if Gazans were given some fundamental human rights and received billions from the Israelis for all of the damage that has been caused. You may find this is what a lot of them want but such is the human loss now some of these Hamas members probably have lost wives/husbands/mothers/fathers/children/brothers/sisters.
If I were them I would never stop, I would fight to the death against fascism, just like our forefathers did back in 1914 and 1939.
We should be supporting Hamas now, they are freedom fighters, they have become the good guys, the dispossessed, if I was in Palestine I would be supporting the Hamas cause, fascism must be defeated, Netanyahu and his cronies have to be brought to justice for their war crimes.