Our history as the political entity known as the United States of America may be very recent, Hille, but it would be the hight of hubris for me to say that the history of the continent on which I live is only recent. And I think there are any number of religions, some of them the religions of the people who were here before 1492, that have not changed substantially since the period of time you refer to as the "middle ages". And yet it would be the height of hubris for me to suggest that they are any less valid than any other religion found in the world today.

As far as repression goes, even modern day Christianity has aspects that many people find repressive. Personally, I find all organised religions to be repressive in one way or another. But that's just me.