Uh... Alright, lots of misinformed people here.
Divine Protection pre 3.0.2 granted full immunity against everything for 6 or 8 seconds, and rendered you completely unable to attack. After you leveled a bit this was replaced by:
Divine Shield is the same as it was pre 3.0.2. You can spell steal it sometimes because of latency.
Divine Protection now lasts 12 seconds and reduces all damage taken by 50% from all sources. So, it is only natural that you are able to spellsteal this. No exploit here.