For the blissfully unititated, so-called “allegorical” readings of literature attempt to find symbolism embedded within narratives. For example, some Christians have perceived a sign of Christ's saving blood in the scarlet rope which Rahab hung from her window to be spared by Israelite invaders (Josh 2). Because of the potential for allegorical readings to stray into fanciful interpretations, most Protestants, especially Reformed Christians, have shied away from consciously applying that hermeneutic to the Bible.
Perhaps it will be surprising, then, to read John Calvin speak favorably about an instance of allegorical methodology. Remarking on Gal 4, he writes that, “towards the close of the chapter [Paul's] argument is enlivened by a beautiful allegory.” Indeed, the Apostle himself admits to perceiving theological symbolism in the story of Hagar and Sarah:
Now this may be interpreted allegorically: these women are two covenants. One is from Mount Sinai, bearing children for slavery; she is Hagar. — Gal 4:24, ESV
In response to this, a pastor inquired of me, “can we really be kept from reading allegorically if Paul did it, and Calvin called it ‘beautiful’ and says Paul ‘enlivens’ his argument thus?”
I, for one, am not opposed to allegorical readings in principle. As we've seen, the Word itself admits of it. My issue is only with certain abusive practices of the method. For instance, if one assumes that every biblical phrase has an intended allegorical aspect then a supercilious search for symbolism is inevitable. I seem to recall a giant of Gath reputed to have six digits on each hand and foot. Was this a figure of mankind (whose number is six) set at odds with God? I think not! More likely, the mention of ol' Twelve Toes simply emphasizes the freakish strength of Israel's enemies.
How then do we responsibly trace allegories in Scripture? I will simply describe how I do so in practice. When reading narratives, I keep an eye out for illustrative qualities that clearly connect the immediate story to broad theological principles. For example, 2 Sam 8 recounts King David's victories and virtues. After defeating Moabite aggressors, he makes the guilty army lay down in three lines. Two of these he orders to be slaughtered; one is spared to become his servants. From this, I draw an analogy. At his return, Christ, our King, will justly avenge himself against the majority of our enemies, while showing mercy to a minority, whom God freely elected from among the guilty (Cf. 2 Thes 1:5-10). Having been graciously pardoned, we now become servants of the King.
Was that the original intent of the human writer? I doubt it. But I am inclined to think the Spirit himself provided for this connection because the image is so consistent with biblical principle it illustrates. If this makes me “allegorical,” call me Clement.