Is the kingdom of God a process of development or social utopia? Let’s ask Vos:
“Side by side with ‘the future age,’ and characterizing it from a less formal point of view, the phrase ‘kingdom of God’ designates the consummate state, as it will exist for believers after the judgment. Jesus, while making the kingdom a present reality, yet continues to speak of it in accordance with its original eschatological usage as ‘the kingdom’ which lies in the future….”
“Although the eschatological kingdom differs from the present kingdom largely in the fact that it will receive an eternal, visible embodiment, yet this does not hinder that even in it the core is constituted by those spiritual realities and relations which make the present kingdom. Hence the figures in which Jesus speaks of it, such as eating, drinking, reclining at table, while not to be taken sensually should not on the other hand be interpreted allegorically, as if they stood for wholly internal spiritual processes: they evidently point to, or at least include, outward states and activities, of which our life in the senses offers some analogy, but on a higher plane of which it is at present impossible to form any concrete conception or to speak otherwise than in figurative language.”
I think the term “analogy” there is helpful, and not used arbitrarily by Vos. Different, but like; described figuratively only in terms of accommodation. Language here is not univocal (i.e. sensual?) or equivocal (i.e. allegorical?), but analogical.
For Vos’ full article on the eschatology of the NT, see pages 979-993 of the International Standard Bible Encyclopaedia Volume II, ed. James Orr (Grand Rapids: Eerdmans, 1952). It can also be found in the Vos’ Shorter Writings that Richard Gaffin edited and P&R published.