God is going to invade, all right: but what is the good of saying you are on his side then, when you see the whole natural universe melting away like a dream and something else – something it never entered your head to conceive – comes crashing in; something so beautiful to some of us and so terrible to others that none of us will have any choice left? For this time it will be God without disguise; something so overwhelming that it will strike either irresistible love or irresistible horror into every creature. It will be too late then to choose your side. There is no use saying you choose to lie down when it has become impossible to stand up. That will not be the time for choosing: it will be the time when we discover which side we really have chosen, whether we realized it before or not. Now, today, this moment, is our chance to choose the right side.

Source: Mere Christianity