The following excerpt is taken from Albert Einstein: The Human Side, Selected and Edited by Helen Dukas and Banesh Hoffman, Princeton University Press, 1979.
On 17 July I953 a woman who was a licensed Baptist pastor sent Einstein in Princeton a warmly appreciative evangelical letter. Quoting several passages from the scriptures, she asked him whether he had considered the relationship of his immortal soul to its Creator, and asked whether he felt assurance of ever lasting life with God after death. It is not known whether a reply was sent, but the letter is in the Einstein Archives, and on it, in Einstein's hand writing, is the following sentence, written in English:
I do not believe in immortality of the individual, and I consider ethics to be an exclusively human concern with no superhuman authority behind it.
In Berlin in February 1921 Einstein received from a woman in Vienna a letter imploring him to tell her if he had formed an opinion as to whether the soul exists and with it personal, individual development after death. There were other questions of a similar sort. On 5 February 1921 Einstein answered at some length. Here in part is what he said:
The mystical trend of our time, which shows itself particularly in the rampant growth of the so-called Theosophy and Spiritualism, is for me no more than a symptom of weakness and confusion.
Since our inner experiences consist of reproductions and combinations of sensory impressions, the concept of a soul without a body seems to me to be empty and devoid of meaning.