How do you protect your home while restaining your front door?
Go to your local lumber yard or big box store and ask about a loaner slab. They know that builders want to send all their stuff out to be finished and will often loan door slabs for no charge. This gives you full functionality of your door while you finish the slab. Take the door dimensions and swing direction (with your back to the hinges).

Now, if you didn't buy your door (or at least your finishing products) from one of these places you may need to do a little more begging. Explain the situation and see what comes of it. An alternative is to buy a cheap scratch-and-dent slab and install it, then sell it on Craigslist or use it for a workbench.