This book contains Paul Mendes-Flohr's reflections on modern Jewish thought: community, the relationship between religion and the state or the diaspora and Israel. Through these texts, Mendes-Flohr will analyse the proposals of Martin Buber and Franz Rosenzweig in the face of the tensions between individualism and the communitarian, or between the particular and the universal; It also introduces us to a fundamental thinker who is little known in our language, Yeshayahu Leibowitz, developing the tension between religion and the State in Israel and between the different ways of interpreting the law that can prevent or lead to the idolatry of reasons of State. Finally, he will seek to reflect on the multiplicity of memberships and ambiguities experienced by secular Jews and will present a little-known article by Gershom Scholem on the tension inherent in the question of who is Jewish today.