Well, we might just need their help if 2012-12-21 galactic precession is going to be an apocalyptic event!. In the movie, those ARKs will not survive because the force of the waves and building debris will ripped it to shreds!.
All those underground bases will be flooded and broken by earth quakes. We need those ID4 type mother-ships to hide behind the moon or behind Jupiter and potentially live there for a couple hundred years.
The nuclear material for the nukes and reactors will contaminate all water!. We are really toast even for a "pole shift" event with a big CME coming sufficiently strong enough to flip the earth's magnetic poles. Then the ETs will need to "clean" the earth before any other re-population can be done.
Well, another potential "Devine intervention" could be that PlanetX (DarkStar), magically pass by at the exact moment when the CME propagates and shields earth from the deadly CME. The gravitational forces might just cause major earth quakes but we would survive pretty much. The prognosis is not great and we can only hope.