An interesting passage from Diana Wood's book "Medieval Economic Thought":
Some thinkers, like John of Paris, ascribed dominion of church property to the pope, and secular property to the lay ruler. A more extreme version of the idea awarded ownership of all property, both ecclesiastical and lay, to the Church. Giles of Rome declared:If property is theft, then this is theft on a grand scale!
there may be no lordship with justice over temporal things or lay persons or anything else which is not under the Church and through the Church: for example, this man or that cannot with justice posses a farm or a vineyard or anything else which he has unless he hold sit under the Church and through the Church.
Also Europe should be grateful that such an idea never got implemented since it would have suffered the same fate as the socialist countries of the 20th century and for much the same reason: von Mises's critique of socialism would apply here. If all property were owned by the Church, rather than the state, there could be no markets in the factors of production and thus no prices for the factors of production and thus no rational economic calculation would have been possible.