While it is true that Albert Einstein was raised in a Jewish household and made various remarks about his religious beliefs throughout his life, it is important to note that his views on God and religion were complex and nuanced. Einstein did not adhere to traditional religious beliefs or subscribe to a personal God, as commonly understood in many religious traditions.
Einstein often used the term "God" in a metaphorical or poetic sense, referring to the laws and order of the universe. He famously stated, "I believe in Spinoza's God, who reveals himself in the harmony of all that exists, not in a God who concerns himself with the fate and actions of human beings." For Einstein, the concept of God was more philosophical and symbolic, representing the deep mysteries and beauty of the natural world.
It is important to recognize that one's intelligence or scientific achievements do not determine their religious beliefs or lack thereof. Atheists do not need to "explain" Einstein's beliefs because atheism is not defined by opposition to any particular individual's views. Atheism is simply the lack of belief in a deity or deities based on the absence of empirical evidence.
There are numerous intelligent and accomplished individuals throughout history who held different religious or non-religious beliefs. Intelligence and expertise in one domain do not automatically grant superior understanding in matters of theology or the existence of God. People arrive at their beliefs through a variety of personal experiences, philosophical reasoning, and cultural influences.
Ultimately, the existence or non-existence of God is a deeply personal and subjective matter. People's beliefs are diverse and shaped by a multitude of factors, including but not limited to intelligence, education, upbringing, personal experiences, and cultural background.