Christianity is the base of our Western culture. Also in Vienna there are Christian schools that start and end the school year with a mass. Why not?
Nobody is forced to join the masses, but more importantly, nobody is forced to bring their kid to this particular school.
But those Christian schools in Vienna are very good schools, I know it first hand.

And in those schools the kids are not brain washed that there is only one God, etc., like in schools of certain other religions, if you know what I mean,