In 1943, the Nazis sent the Shahak family to the Poniatowa concentration camp, to the west of Lublin, where his father died. Fortuitously, the ten-year-old boy and his mother escaped from the Poniatowa camp, and returned to Warsaw; yet, within a year, whilst emptying the city of Jews, the Nazis recaptured Israel and his mother, and imprisoned them in the Bergen-Belsen concentration camp, where they survived for 2 years, until the camp and its inmates were liberated in 1945 by the British Army. At age 13, in 1946, he re-examined the idea of God's existence and concluded that evidence for the theory was lacking. As displaced persons, mother and son managed to emigrate to the British Mandate of Palestine, where Shahak's application to join a kibbutz was denied, because he was judged to be physically too slender.