Some definitions are required. Precisely when are you rich?
Well, I'll use income as our metric here for simplicity's sake.
In St. John Chrysostom's time he would likely have had in mind the
latifundia, the great landed-estate owners and the senatorial class who could boast on average between 400,000 sestertii and 1,000,000 sestertii. Also, the slightly less well-off equestrian class.
I'm not sure what this would be, adjusting for inflation, in today's terms but certainly in the millions, half a billion and billions of dollars-type territory.
Our mega-millionaires and billionaires are the super-rich, the 0.01%.
Although, to be among the top 1 % of U.S. earners, a family needs an income of at minimum $421,926.
But the simple principle Chrysostom enunciates is that whatever a person has in superabundance or superfluity, beyond what they need to satisfy their needs and live comfortably, belongs to the needy in his mind. If we hoard it and don't spread it out either through our taxes or philanthropy, then we're literally denying the indignant what belongs to them and committing theft on the poor.
The extent of this would, naturally, vary greatly between someone earning over £400,000 and someone earning £26 million and then again billions like Bezos.
As for the word "
injustice": the very fact of extreme disparity in income, of massively uneven distribution of wealth, was itself proof of abuse for Chrysostom and he believed the law merely legitimated a profoundly unjust situation. If I may quote the scholar Sarah Drakopoulou Dodd:
"Chrysostom conceived the nature of ownership essentially as that of a dynamic function of sharing the world's wealth to meet he requirements of a life of dignity for all.
According to Chrysostom, human welfare depends upon an abundance of goods, the general peace and a reasonably equitable distribution of wealth. If these three conditions are satisfied, then one can commence the quest for an approximation of a welfare state (vol. 58, Homilies on the Psalms, 341B).
Chrysostom in his Homilies on the Priesthood stressed that love and friendship among men increase when there are no extreme inequalities in the distribution of possessions...
The Fathers, and especially Chrysostom, believed that the role of taxation was mainly the redistribution of income and wealth. He was in favour of progressive taxation, condemning the equal fiscal treatment of rich and poor"
(Ancient and Medieval Economic Ideas and Concepts of Social Justice (2000), p.195)
His contemporary, St. Augustine of Hippo dreamt of a future in which the landless poor would be maintained by social welfare distributed by the government via progressive taxation:
CHURCH FATHERS: City of God, Book V (St. Augustine)
....the admission of all to the rights of Roman citizens who belonged to the Roman empire, and if that had been made the privilege of all which was formerly the privilege of a few, with this one condition, that the humbler class who had no lands of their own should live at the public expense — an alimentary impost, which would have been paid with a much better grace by them into the hands of good administrators of the republic.
Chrysostom argued that the equal right of all to the use of the wealth of the earth was akin to their right to breathe the air:
CHURCH FATHERS: Homily 12 on First Timothy (Chrysostom)
Is this not an evil, that you alone should have the Lord’s property, that you alone should enjoy what is common?
Mark the wise dispensation of God. That He might put mankind to shame, He hath made certain things common, as the sun, air, earth, and water, the heaven, the sea, the light, the stars; whose benefits are dispensed equally to all as brethren.
We are all formed with the same eyes, the same body, the same soul, the same structure in all respects, all things from the earth, all men from one man, and all in the same habitation. Other things ... He hath made common, as baths, cities, market-places, walks.
(Schaff, 1886, 13, p.448).