I've been "stuck" in Genesis for so long, mining it deeply for several years now, so I was glad that my Community Bible Study decided to go through Exodus! Most people are probably not very thrilled with reading those early Old Testament books, but I love them!
I love the Old Testament books for the revelations of Jesus Christ: from the Creator joyfully bounding over his new creation to the heartbroken companion who must exile Adam and Eve, from walking to see how bad Sodom & Gomorrah actually are before destroying them to stopping Abraham's downward arcing arm to save Isaac, from the top of a stairway up to Heaven to wrestling in the dark with Jacob, from calling Moses aside from deep within a bush, engulfed in flames but not burned up, to the front of at least a million Israelites he has rescued by his own hand from slavery in Egypt.
After studying the details of the plagues and the gods they challenged, I spent some time thinking about the bigger picture of how God rescued Israel from Egypt—why he did it his way, his main purpose, and so on.
It's easy to assume God did all that He did in Egypt to liberate Israel—that's obviously a part of it! But it can't be all of the reason because God doesn't stop showing up in power after they are freed. He doesn't leave them on their own. And he doesn't take them on the shortest route to the Promised Land. He could have miraculously herded them through the Philistine lands safely, which would have been the shortest route since he can do anything!
God could have rescued Israel from Egypt in a thousand ways and done things differently at each turn. Instead, he unfolds a plan where they spend an entire generation in the desert together, dwelling with him in their midst.
God tells us his plan is ALWAYS to dwell with us and the Bible clearly reinforces this at every revelation. This is ALWAYS the overarching purpose of all he does:
"I will be their God, they will be my people, and I will dwell in their midst." A holy God among a holy people.
Instead of a shortcut, God leads Israel out of Egypt with a fiery, smoking pillar (much like Abraham saw when God ratified covenant with him), that burned brightly and visibly at night. They first encamp at what becomes another "rock and hard place"—where only God's deliverance can get them through.
It is at this first encampment of the newly-freed Israel that we see God is not yet done with Egypt, which is to me, more proof that the purpose of all that Egypt just went through was not just for delivering Israel from slavery.
God declares in Exodus 14:4 and 14:17-18 that he will again harden Pharaoh's heart so that Pharaoh will pursue the Israelites and God will gain honor over Pharaoh and over all his army so that the Egyptians will know that he is the Lord.
Now God declares he has set his sights on Pharaoh, the demi-god he thinks he is, and all he represents, as his final target. No longer going after lesser gods who merely support Pharaoh's reign, God goes after Pharaoh and his army—the greatest fear for Israel and the surrounding countries.
God will demonstrate for all of Israel, Egypt, and the surrounding countries that he is the only all-powerful God. All the plagues in Egypt have brought us to the final, inevitable showdown.
It doesn't take long. When the waters engulf Pharaoh and his army—when Egypt's main god is completely destroyed—it is clear to Israel who the real God is.
And when the Israelites saw the mighty hand of the Lord displayed against the Egyptians, the people feared the Lord and put their trust in him and in Moses his servant. - Exodus 14:31
Moses' song clearly tells us the purpose for all of this display of strength and power:
You will bring them in and plant them on the mountain of your inheritance—the place, Lord, you made for your dwelling, the sanctuary, Lord, your hands established. - Exodus 15:17
Later, in Hebrews 8, which repeats Jeremiah 31:31-34, we are granted more of the full picture when God reveals his new covenant:
“The days are coming, declares the Lord,
when I will make a new covenant
with the people of Israel
and with the people of Judah.
It will not be like the covenant
I made with their ancestors
when I took them by the hand
to lead them out of Egypt,
because they did not remain faithful to my covenant,
and I turned away from them,
declares the Lord.
This is the covenant I will establish with the people of Israel
after that time, declares the Lord.
I will put my laws in their minds
and write them on their hearts.
I will be their God,
and they will be my people.
No longer will they teach their neighbor,
or say to one another, ‘Know the Lord,’
because they will all know me,
from the least of them to the greatest.
For I will forgive their wickedness
and will remember their sins no more.”
Every plague that happened was to demonstrate to the world and to Israel that Yahweh, the only God of the universe, had set them apart and wanted them for himself. He offers Israel (and to us) the answers to their deepest longings: to be known and to belong.
Everything that happened in Egypt —and in my opinion, everything that God does—is for the main overarching purpose of dwelling with us and in us. On eagle's wings I carried you, he says. I have brought you to myself. A holy God dwelling in the midst of and unified with, his holy people.
Grace dwells with us.