The middle class' income is not ongoing either. It is limited.
Yet the Pope is in favor of decreasing it in order to distribute it to others.
Not arguing in favor of the Pope’s preferred policies, whatever those are. Merely pointing out that sale of church buildings and works of art will not fund much in the way of ongoing redistribution of wealth.
The French Revolution attempted to finance itself by looting the Church, at a time when the Church controlled vast amounts of actual income-producing assets, mostly farmland. Didn’t work out too well.