Miracles are not for amusement but have a goal (for participants and for us, who live centuries later). Some of these goals are:
to show God does what he promises (Exodus 3:12);
to give faith:
to Israel (Exodus 3:12),
to Jesus’ disciples (John 2:11),
to us (John 20:30–31);
to make us praise the Lord for his grace and compassion, Psalm 111:4:
He has caused his wonders to be remembered; the Lord is gracious and compassionate.
In his work God shows that he is who he is, i.e., Yahweh.
Today God also does wonders—natural and supernatural. Every conversion is a miracle: only God can make a heart of flesh from a heart of stone. God does miracles like healing, and he gives signs that he will restore the good creation in his kingdom. But he does it when and how he decides to do it. We cannot try to manipulate him by pious
prayers or rituals.
God gives signs of his work, for example, in baptism and the Lord’s Supper. We call them signs and seals
of the covenant (just like circumcision is called a sign and seal, Exodus 3:15). They help us to trust the Lord.
20 So I will stretch out my hand and strike Egypt with all the wonders that I will do in it; after that he will let you go.