What has happened in the old Palestine mandate is partition and a partial exchange of populations. I say partial because while Israel allowed Arabs to stay if they wanted, all Jews were expelled from the West Bank and Gaza, and almost entirely cleared out of the Middle East.
This is no different from what happened around the same time in India and Eastern Europe. Muslims went to Pakistan (mostly) and Hindus to India (almost entirely). Germans left Eastern Europe and went to Germany. In each case the refugees were given citizenship rights and absorbed into the population.
What is different here is that the surrounding Arab states refused to give their refugees citizenship rights, which makes them essentially stateless, and kept them cooped up in refugee camps, aided and abetted by the UN.
IMHO what the Arabs have done is a gross violation of the Pali's human rights, done deliberately to try to destabilize the region and block the chances of peace with Israel. If the Cardinal cared a fig for human rights and world peace, this is the crime he would denounce.