Layered magnetic field surrounding our Earth cant protect us?

Most people don't realize just how big a deal it is to try moving an asteroid the size of Mount Everest. Hollywood would have us believe that all we need to do is put a few nukes around it and it will blow to smithereens. In fact, we simply don't have the technology to divert an asteroid attack. And since the odds of one actually hitting us anytime soon are vanishingly small, there's only a small amount of funds being invested in solving the problem.