I have heard it said that about 200 million people will be saved by the Rapture on 21st May. The mass of that number of people is about 10 billion kg.  To be raptured, that mass is going to have to get to escape velocity: 11.2 km/s.  The energy that will need is about 6.3 x 10^17 Joules.  That's equivalent to about 8,000 Hiroshima bombs going off.