How does the Resurrection fit into Christian theology?
One way of looking at it is to say that the resurrection of Christ is evidence that his sacrifice was accepted by God: our sin placed us in moral debt to God and Christ has paid that debt in full. Instead of a receipt, we get a resurrection.
That's one angle on it.
Another angle is that the resurrection serves as a sign that Jesus is who he claimed he was. He claimed to be the Messiah, the One who would rescue us from sin and death and the devil. His death was to accomplish our rescue. How do we know he was who he claimed to be? Well, though he died a sinners death, he could do something to show us that death, sin and the devil had no claim over him. He could return to the place of the living and then we'd know who he is. Instead of showing his ID, he just comes back to life.
That's another angle on it.
But we rarely need our receipts. I usually throw mine away. And as far as IDs go, since Jesus can make his own wine...well, hmmm...let's just say my ID isn't the most important or frequently used thing in my wallet.
For most of us, for most of the year, the resurrection barely registers on our radar. Should it?