Impossible? No, just unlikely.
The medium length Jesus Christ ambigram displayed to the left is a nice generic design that makes you do a double take.
A quick glance will show you that ambigrams really are ambi-guous depending on how you read them. This design can be read as 'Jesus' one way and can be read as 'Christ' the other way.
If you can't read upside-down (without breaking your neck!), rotate the entire design by mousing over it.
All items in the FlipScript store are already displaying the Jesus Christ ambigram. To see them, use the menu bar at the top to navigate to an item and you will see the Jesus Christ ambigram everywhere! Don't forget that you can change your mind (and your design) at any time by using the blue 'Create a New Design' button on the top of every page.