"It is always necessary to stand up for individual liberties, for minorities, for respect and for the fundaments of democracy – for what it takes for a free and open society to function with stability," the cardinal said.
"It is a kind of symbiosis that requires constant work. And if you turn away for just a second, you'll soon find out. The dangers [of neglect] become apparent very quickly."
The cardinal said that in his view, protecting rights in the European Union depends upon "making progress towards a social Europe."
We are interconnected with each other through various forms of solidarity," he said.
"Through the European Union, for example, through treaties, through parliament, through guiding principles. We can't do this without each other. We are staring down the barrel of Brexit right now. Our interconnectedness necessitates that we stand up for each other so that something positive can be the outcome."
Asked about popular movements in Poland and other eastern European nations that seem to represent a shift toward "non-liberal democracy," the cardinal said that "dialogue is necessary and takes place within the framework of the EU. There are cornerstones on which the various constitutions are based. But there are differences in Europe. And they are legitimate."
A critical factor, Marx said, is that "a political majority does not reflect the whole population," he said. "The population includes everyone, including minorities. An incumbent party cannot say: We are 'the people' to justify turning things upside down and no longer taking other positions and minorities into account."