Albert Einstein Einstein did not return to Germany. He settled in the United States and became an American citizen in 1940. On the eve of World War II, he endorsed a letter to President Franklin D. Roosevelt alerting him to the potential development of "extremely powerful bombs of a new type" and recommending that the US begin similar research. This eventually led to the Manhattan Project. Einstein supported the Allies, but he generally denounced the idea of using nuclear fission as a weapon. He signed the Russell–Einstein Manifesto with British philosopher Bertrand Russell, which highlighted the danger of nuclear weapons. He was
Religious and philosophical views of Albert Einstein Religious and philosophical views of Albert Einstein Albert Einstein's religious views have been widely studied and often misunderstood. Einstein stated that he believed in the pantheistic God of Baruch Spinoza. He did not believe in a personal God who concerns himself with fates and actions of human beings, a view which he described as naïve. He clarified however that, "I am not an atheist", preferring to call himself an agnostic, or a "religious nonbeliever." Einstein also stated he did not believe in life after death, adding "one life is enough for me." He was closely involved in his lifetime with