Allegory is a story with a hidden story; a deeper meaning. If the literal sense of the Bible is words representing things then the allegorical sense is things representing things. When Scripture speaks of “the temple” the literal sense sees a building in Jerusalem but the allegorical sense sees the building as an allegory for the “true” temple; Jesus Christ’s body (Jn 2:21). The literal sense tells us the temple is the dwelling place of God with the purpose of offering sacrifice. Knowing this, we can see how Jesus’ body is also the dwelling place of God with the purpose of being sacrificed. Noah’s flood isn’t just a flood, it’s an allegory of baptism (1 Pt 3:20-21). The “things” (temple/flood) represent other things (Jesus’ body/baptism).
Many stories have a moral to them. Aesop’s Fables are perfect examples of this. A story is told and a moral or lesson is derived from them. God has authored the Bible in a very similar way by using allegory to help us understand the truth of the narrative.
To flesh this out, let’s look at Jesus command that we must be “born again of water and the Spirit” (Jn 3:5). Some Christians think we must be baptized with water while others say a prayer is sufficient for this event.
This is very difficult to determine from this passage alone and also from just the New Testament books alone; but let’s see we can learn from Old Testament narratives that may have a meaning held within them.
In Genesis 1 we see the creation of the world. What’s present? The Spirit hovering over the water (Gen 1:2). The world was “born” as the waters fell away and the dry land appeared.
In Genesis 7-8 we see the re-creation of the world with the flood. Again we see the waters fall away and dry land appearing. What tells Noah this? A dove (Gen 8:8-12).
In Exodus 14 the Spirit of God separated the Red Sea and the Israelite people were reborn from slavery into new life. How were they reborn? Through physical water and the Spirit.
In Luke 3 Jesus is baptized physically in water and the Spirit descends on him “like a dove” (Lk 3:22).
Catholics roll this all together and say when God creates or re-creates something He uses real, physical water and the Spirit operates as well. St. Peter agrees when he points out “In it [Noah’s ark] only a few people, eight in all, were saved through water, and this water symbolizes baptism that now saves you also” (1 Pt 3:20-21). The allegorical sense of the Bible helps us see things that aren’t obvious in the text of a specific passage. Sometimes a flood is just a flood, but God can use a flood to tell us even more.