Biblical typology, succinctly defined, is a method for interpreting everything in the Old Testament (characters, objects, incidents, numbers, colors, etc.) as prophetic "types" that find their fulfillment in their New Testament "anti-types." For example, the Old Testament tale of how Jonah spent three days in the belly of a giant fish may be factually true, but its deeper significance lies in the fact that it prefigures Christ's three days in the tomb--as Jesus himself explained in Matthew 12:40.  Does biblical typology shed any light on the design and intention of Beowulf, a vernacular Anglo-Saxon poem about a pre-Christian hero who battles man-eating monsters, dragons, and hostile neighbors? The short answer: a great deal of light. For William Helder's study of Beowulf and biblical typology provides a deeply learned and highly illuminating account of the way in which scriptural typological codes, mediated by the liturgy and commentary traditions, shed light on the poem's action, characterization, imagery, and themes. 
As Helder is quick to acknowledge, the idea of reading Beowulf through the lens of biblical typology is not new. There is no disparagement intended in pointing out that Helder's book conducts an extended, open debate with the ground-breaking though controversial studies of the biblical-allegorical influence on Beowulf by Margaret Goldsmith.  In her landmark essay, "The Christian Perspective in Beowulf" (1962), Goldsmith set out the essential lines of interpretation that Helder also follows, and upon which he helpfully elaborates. Goldsmith's succinct statement regarding the Christian texture of Beowulf is worth quoting, as it reflects the basic assumption of all the Christian-allegorical interpretations of the poem that have appeared, including the book under review:
[Beowulf] is a poem about the heroic life, written by a Christian poet, and such a theme could not be divorced from Christian faith and hope, save by a deliberate effort on the poet's part to recreate the past with the detachment of a scientific historian. There is no conceivable reason for the poet to adopt such a course. Nor should we expect him to chase from his mind the traditional Christian attitudes toward the Good Fight, when imagining a fight against monstrous creatures whose malice springs ultimately from the Ancient Enemy. Undeniably, [Beowulf] has a historical perspective, but even if the poet possessed the fictive power to create a wholly heathen Beowulf, he and his audience would still measure the hero's beliefs about life against their own. 
This reasonable proposition regarding the mindset of the contemporary Christian audience of Beowulf needs only to be qualified by the recognition (brilliantly expounded by Larry Benson) that the Beowulf-poet does in fact adopt "a historical perspective," and is at pains to demonstrate the tragic distance between his contemporary Christian audience and their noble but doomed pagan Germanic ancestors--whence much of the poem's emotive power. 
That having been said, how are we to evaluate the social and religious worlds of the Danes and the Geats depicted in Beowulf? Take the case of the great Hall, Heorot, where the Danish King Hrothgar presides at lavish scenes of feasting, drinking, and gift-giving to his loyal men for their service in war and peace, until the man-eating monster Grendel attacks at night and puts an end to the joys of the hall. What is the significance of Heorot? Is this hall a type of Babylon, as Goldsmith suggests, or is it a type of Jerusalem or the City of God, as Helder sees it? The crux of the matter is, how can we know for sure? For Goldsmith, the Danes are anything but admirable, damned by their pre-Christian striving for material success (call it cupidity), whereas for Helder, the Danes are depicted favorably, as the poet's allusions to biblical imagery pre-figure the positive themes of baptism, redemption, and salvation. This clash of antithetical interpretive positions nicely illustrates Augustine's classic definition of the inherently antithetical nature of biblical symbolism. According to Augustine, the same item can signify de bono and de malo--a lion as a symbol of the devil, and also a lion as a symbol of Christ!--depending on the context.  But what are the "criteria of corrigibility?" 
Here is where Helder's book breaks new ground and deserves a wide readership among those interested in the religious texture of Beowulf in particular, and the typological networks that are pertinent for the appreciation of Anglo-Saxon poetry in general. As Helder demonstrates, the influence of Psalms imagery, by way of the liturgy and Psalms commentaries, is especially pervasive. Major typological motifs in Beowulf that are discussed are indicated by the chapter titles: Heorot and the Song of Creation, Hrothgar and the Yearning Hart, Ice-Bonds and the Rising Sun, Beowulf and Springtime Heroism, Doomsday and the Dragon's Hoard. If the Devil is in the details, Helder's close readings and apt quotations from liturgical and patristic sources demonstrate that angels, devils, baptism, sin, and salvation subtly and evocatively shadow the poem's pre-Christian characters throughout. Many readers have felt this to be the case, and now they have a firmer basis--not just faith or wishful thinking, but textual evidence--to bolster their conviction.
The book is well written and carefully edited. To give the last word to Alvin A. Lee, the distinguished Old English scholar who contributed a foreword to the book, and supervised Helder's dissertation on Beowulf:
Helder's tone tone is quiet and non-polemical, as he accumulates the evidence and focuses on a host of illuminating parallels among texts, and then considers their possible or probable connotations in Beowulf. He never forgets that he is dealing with a heroic poem that is not a doctrinal treatise or condemnatory moral tale, as some scholars have surmised. This welcome book casts a great deal of light on one of the verbal treasures of our culture. (ii-iii)
1. For a landmark discussion of typology, see Erich Auerbach, "Figura" (1944), trans. Ralph Mannheim, in Auerbach, Scenes from the Drama of European Literature (1959; rpt. Minneapolis, MN: University of Minnesota Press, 1984).
2. Full disclosure: this reviewer's essay on "Beowulf and the Bible" came out too late to be noticed in the book under review. See Lawrence Besserman, "Beowulf and the Bible," in "Teaching Beowulf in the Twenty-First Century, eds. Howell Chickering, Allen J. Frantzen, and R. F. Yeager (Medieval and Renaissance Texts and Studies, 449; Tempe: Arizona Center for Medieval and Renaissance Studies, 2014), 147-157.
3. Margaret Goldsmith, "The Christian Perspective in Beowulf ," in Comparative Literature 14 (1962): 71-90; repr. in Studies in Old English Literature in Honor of Arthur G. Brodeur, ed. Stanley B. Greenfield (Eugene: University of Oregon Press, 1963), 71-90; and repr. again in R.D. Fulk, ed. Interpretations of "Beowulf:" A Critical Anthology (Bloomington: Indiana University Press, 1991), 103-119. Goldsmith's book-length exegetical interpretation of the poem is entitled The Mode and Meaning of "Beowulf" (London: University of London-Athlone Press, 1970).
4. Goldsmith, "The Christian Perspective in Beowulf ," 76.
5. See Larry D. Benson, "The Pagan Coloring of Beowulf," in Old English Poetry: Fifteen Essays, ed. Robert P. Creed (Providence, RI: Brown University Press, 1967), 193-213.
6. On the possibility of contradictory significances of a figurative locution in the Bible, depending on context, see Augustine, On Christian Doctrine, trans., with an introduction, by D. W. Robertson, Jr. (Indianapolis, IN: Bobbs-Merrill, 1958), 99-101 (III.xxiv-xxv.34-7); p. 100 (xxv.36) on the ambiguous lion.
7. The term was introduced by Morton W. Bloomfield, "Symbolism in Medieval Literature," Modern Philology 61 (1958): 73-81; repr. in Bloomfield, Essays and Explorations: Studies in Ideas, Language, and Literature (Cambridge, MA: Harvard University Press, 1970), 201-216. Bloomfield raised the question of "criteria of corrigibility" in order to criticize what was then a popular method for uncovering supposed (and frequently tenuous) allegorical or symbolic senses in medieval secular texts.