Irresponsible thoughts on Hermeneutics, or Is Israel's Kingdom the kingdom of God?

Gregory of Nyssa believed that when Jesus prayed “your kingdom come,” the Lord referred to the Holy Spirit (Matt 6:10). The Spirit of Jesus came down, and God’s will was done on earth. God reigns in this way. 

Does any particular aspect of the Lord’s prayer lead to Gregory’s conclusion? It depends on how one answers the following question: Is the kingdom of Israel the kingdom of God? If one answers no because no particular text ties Israel’s kingdom to God’s kingdom, then one will almost certainly say no to Gregory’s interpretation. 

On the other hand, if one answers yes the kingdom of Israel is the kingdom of God, that is, the church in the Old Testament that prefigures the church in the New Testament bound together by the Spirit of God into the Body of Christ, then it becomes not just possible but really a quite plausible understanding of Jesus’s prayer. 

The difference I have described here can also, and probably very irresponsibly, map unto the differences implied in nominalism and realism. Nominalists claim that two things are similar because their particular traits seem similar; and we might even call them identical for this reason.

A realist says two things are similar or the same because they share in something real. So the kingdom of God is something real—God’s reign by his Spirit. The Kingdom of Israel would represent a visible manifestation of that invisible reality. So tying Israel’s kingdom to the church of God as both testifying to the same reality under different dispensations results from realism. 

The reformers particularly adopted this view, at least when it came to identifying the church in the Old Testament. Or rather, if Ephraim Radner is correct (at least for Calvin), then the reformers brought Scripture into their present. Calvin wrapped the Old Testament narrative into his life’s narrative. The Bible is the world into which our world fits. 

Perhaps I am not so irresponsible to attribute differences in interpretation on such matters  to nominalism and realism. Of course, this represents one of many causes. I am not claiming a single cause for such divergent points of interpretation. 

So maybe I am more responsible than I think? Someone will tell me in the comments, I assume, since this is the internet.