Being circumcised does not make you a Jew! Being born to a Jewish woman makes you a Jew (or converting). BUT! Circumcision is central to participating in orthodox Jewish life and is deeply connected to attempts at forcing assimilation onto the Jewish people. A push not to circumcise a Jewish boy can be interpreted as an attack on the Jewish community to not practice their religion/not identify as Jewish. Go read the history of Jewish women being pushed of the walls of Jereusalem for allowing their male babies to be circumcised, and laws passed (and repealed) by the Greeks and Romans to forbid circumcision in order to promote assimilation of the Jewish people. Go read about more modern attempts to promote assimilation in Russia under Stalin and later communist Russia. I believe that Jews who circumcise for non religious reasons, in part do so out of a fear of assimilation and loss of Jewish identity.
Three killed after car bomb explodes in Sana'a, Yemen (Reuters)