It is difficult to understand why evangelicals would allegorize the Scriptures that clearly teach a physical, earthly reign of the Lord Jesus Christ on the throne of David
1. Because the Bible, both Testaments [including almost all of Jesus' teaching], contains multiple books that are either clearly symbolic, are largely figurative or contain passages and stories that suggest the propriety of a figurative interpretation.
2. Because any predominantly "standard" or literal interpretation of the Bible runs into tensions (unsolved propositions, incoherence, contradiction, etc.) which require the spiritual or metaphoric meaning to resolve. Resolved tensions = higher degree of truth.
3. Because some believe that God speaks yet today through metaphor in His word in both subjective/personal and objective/universal ways despite the fact that attempts by persons trying to hear and respond to a higher spiritual union or relationship with God have always been beaten down by organized religion which attempts to control what God is allowed to say.
Because God uses literal elements as the basis for teaching higher spiritual principles, it's possible that the literal elements themselves--the "clear...physical, earthly reign of Christ on the throne of David"--may be symbolic of something higher.
That God has chosen to speak to us strongly in metaphor is likely because He designed us to receive information this way:
In classical theories of language, metaphor was seen as a matter of language not thought. Metaphorical expressions were assumed to be mutually exclusive with the realm of ordinary everyday language: everyday language had no metaphor, and metaphor used mechanisms outside the realm of everyday conventional language. The classical theory was taken so much for granted over the centuries that many people didn’t realize that it was just a theory...
As a cognitive scientist and a linguist, one asks: What are the generalizations governing the linguistic expressions re ferred to classically as poetic metaphors? When this question is answered rigorously, the classical theory turns out to be false. The generalizations governing poetic metaphorical expressions are not in language, but in thought: They are general map pings across conceptual domains. Moreover, these general princi ples which take the form of conceptual mappings, apply not just to novel poetic expressions, but to much of ordinary everyday language. In short, the locus of metaphor is not in language at all, but in the way we conceptualize one mental domain in terms of another. The general theory of metaphor is given by characterizing such crossdomain mappings. And in the process, everyday abstract concepts like time, states, change, causation, and pur pose also turn out to be metaphorical. The result is that metaphor (that is, cross-domain mapping) is absolutely central to ordinary natural language semantics
The Contemporary Theory of Metaphor, George Lakoff (1992)
The Word of God can be best understood when it is read in a literal, normal, and plain sense. A normal reading of Scripture is synonymous with a consistent literal, grammatical, historical hermeneutic.
Is this the teaching of God or man, and why does it seem to run contrary to our design?