An unsigned credit card represents a unique kind of threat to our nation. Specifically, it’s the kind of unsubstantiated threat that can be resolved by borrowing a pen and signing the back of your card.
When you do this, security flows through the pen through some property of Bic-enabled transubstantiation and onto the card and the entire country upon which the card is sitting (via the counter). The agent selling postage is now able to compare the signature at the back of the card against the signature on the receipt and verify that it is indeed the same person.
This is just more proof that the Jesus favors the United States above all of the other states out there.