For our parts we should just be determined to carry out our mission against all opposition, demons, nuclear war, whatever. The whole universe is finally subject to certain annihilation by the will of Krsna, but devotional service is eternal and is the only certain way one can save himself from devastation. We can preach all over the world that the only way to be saved from collective and individual devastation is to take to the chanting of Hare Krsna. In short, this material world is a very precarious place therefore we should always chant Hare Krsna and seek Krsna's protection.
Letter to Makhanlal, 22 June, 1973