Removable Hedge?

Some claim that God puts a hedge of protection around Christians, and at times He may then remove that protection, yanking the hedge away as some sort of test.
 
This was David’s question when he wrote us an email, wondering if God sometimes revokes His protective presence from believers.
 
In this short video clip, I address this important question: First, is there a protective hedge, and second, is it sometimes removed to teach us a lesson?