Einstein biographer (and idolizer) Walter Isaacson wrote a 2009 Atlantic Monthly magazine article on How Einstein Divided America's Jews. He makes it clear that being a Jew was extremely important to Einstein, and how he was politically dedicated to the Zionist cause.
So when he arrived in New York in April, he was greeted by adoring throngs as the world’s first scientific celebrity, one who also happened to be a gentle icon of humanist values and a living patron saint for Jews. ...I think of Judaism as a religion, but Einstein was not religious in the way that Christians use the word. He did not believe in a personal God, or attend religious services, or pray, or have faith in a spiritual world. To him, being a Jew meant that he was born a Jew and that he was a believer in Jewish identity politics.
“In your letter,” he responded, “I notice that the word Jew is ambiguous in that it refers (1) to nationality and origin, (2) to the faith. I am a Jew in the first sense, not in the second.”
There is often controversy on the Albert Einstein Wikipedia article about whether to prominently identify him as a Jew. Some argue that Judaism is a religion and Einstein was not religious, or that Einstein is famous for his physics and that his Jewishness is only of interest to prejudiced people. However it seems obvious that Einstein's Jewishness is essential to any biography. His Jewishness was extremely important to him, even more important than being German or being a naturalized American. He is mainly famous for being a physicist, but he is also frequently quoted for his opinions on God, religion, and peace. He was an active Zionist and a Nazi refugee. People are fascinated with the details of Einstein's life, and his Jewishness is one of the first things they learn.
A reader supplies Einstein's 1921 interview/essay on How I Became a Zionist.