I would argue that the EU is quite a successful organization given the task of setting up general market rules for 26 countries.
Obviously there is a lot to criticize about the EU and I can offer you a gigantic list there too. However, I do not see any clear failure of the EU’s approach as a single market so far. Additionally part of the philosophy was establishing peace in a region that was torn up by wars for a lot longer than Christianity exists. I would argue the EU was quite successful there too.