Why should the Israelites follow God and believe in him?
Sure, the philosophy and the Commandments are important, but the wonders, magic, and tricks are really what seal the deal. Remember, this isn't just about getting the Israelites out of slavery. It is about proving that God can compete fiercely among a pantheon of other regional gods. Pharaoh included.
When we hear the word "miracle" today, we think spirituality, moving experiences, and epiphanies. Not so back in the day. The ancients didn't have meteorologists, which meant they had a lot of 'splainin to do when it came to natural phenomena. And how to explain it all? God's magic.
Because of that, God's power and natural power are nearly one in the same. When the writer describes the powers of the Egyptian priests, he talks about their use of "secret arts" (7:11). Yep, God has power, they have arts.
God's first big trick is the whole burning bush thing. Read the detailed summary of "Chapter 3" for more deets, but suffice it to say, God's magic is what lets him communicate with Moses and show him who's boss. (P.S. It's on fire, but it doesn't burn? Don't try this at home.)
In 4:1-9, God gives Moses the ability to perform three tricks—leprous hand, staff becomes snake, water into blood—to prove to the Israelites that he's legit. This power transfer makes Moses an instrument of God's natural power. People's reactions will look something like this: "Wow, you can do what God does! You must be powerful."
The people also experience more direct expressions of God's abilities that are designed to shock and awe. The "pillar of fire" (13:21:22), the parting of the Red Sea (14:15-19), and the manna storm (16:13-15)—God really loves using nature to help out the Israelites.
But the magic isn't always so straightforward. Take a gander at this passage:
Then Amalek came and fought with Israel at Rephidim. Moses said to Joshua, "Choose some men for us and go out, fight with Amalek. Tomorrow I will stand on the top of the hill with the staff of God in my hand." So Joshua did as Moses told him, and fought with Amalek, while Moses, Aaron, and Hur went up to the top of the hill. Whenever Moses held up his hand, Israel prevailed; and whenever he lowered his hand, Amalek prevailed. But Moses' hands grew weary; so they took a stone and put it under him, and he sat on it. Aaron and Hur held up his hands, one on one side, and the other on the other side; so his hands were steady until the sun set. And Joshua defeated Amalek and his people with the sword. Then the Lord said to Moses, "Write this as a reminder in a book and recite it in the hearing of Joshua: I will utterly blot out the remembrance of Amalek from under heaven. (17:8-14)
Hilarious, right? God is parting the waters of the Red Sea, but he can't prevent Moses's arm from getting tired. It's like the coolest Survivor challenge ever. What's the takeaway? God has great power, certainly, but it's by no means absolute at this point in the Bible.