There are several reasons why people believe that Albert Einstein was not religious:
Statements about religious beliefs: Einstein made various statements throughout his life that indicated a skeptical or non-traditional stance toward religion. For example, he wrote a letter in 1954 where he referred to the idea of a personal God as a "childish superstition" and expressed his belief in a more impersonal concept of God.
Emphasis on scientific inquiry: Einstein was deeply committed to the scientific method and the pursuit of knowledge through empirical observation and logical reasoning. His focus on rationality and evidence-based thinking led some to believe that he viewed religious claims as lacking in empirical evidence and therefore not compatible with his scientific worldview.
Rejection of organized religion: Einstein was critical of organized religious institutions and their dogmas. He expressed reservations about religious hierarchies, rituals, and the conflicts arising from different religious traditions. While he acknowledged the ethical and social aspects of religion, he often emphasized the importance of individual moral responsibility over religious authority.
Einstein's views on determinism: Einstein's work in physics, particularly his contributions to the theory of relativity, had implications for philosophical concepts such as determinism. Einstein believed in a type of determinism, where physical laws govern the behavior of the universe, which some interpret as incompatible with notions of religious free will or divine intervention.
Einstein's Jewish heritage: While Einstein was born into a Jewish family, his religious beliefs and practices evolved over time. He did not adhere to strict religious observance and identified more with a cultural or philosophical Jewish identity rather than a religious one.
It's important to note that Einstein's views on religion were nuanced and evolved throughout his life. He did not categorically deny the existence of a higher power or spiritual dimension but approached religious and metaphysical questions from a scientific and philosophical perspective. Despite his skepticism toward traditional religious concepts, he also expressed awe and wonder at the mysteries of the universe, which some interpret as a form of spirituality.