In comparing Exodus 35 – 40 with 25 – 31, you will notice nearly a verbatim repetition. With the exception of a dozen verses, we could have ended the book with Exodus 34. So why bother with the last six chapters?
If we had ended with chapter 34, we would have gotten the directions for building the tabernacle, we would have seen Israel’s unfaithfulness with the golden calf, her repentance and her forgiveness. Ending with chapter 34 would have tied up the book in a nice package.
But it would have been an incomplete package.
God doesn’t save us, forgive us and reconcile us just to have us go our own way. The last chapters of Exodus emphasize that the penitent and forgiven must also be obedient. When they are, God takes up His residence among them.
God doesn’t call us just to redeem us, but to remake us that we might do His will.