This book can best be described as a study in comparative religion: It compares Islam’s main branches, the Sunni and the Shi`i (or Shi`ite). In so doing, it employs the medium of correspondence between two theologians, one from each branch. The objective behind its publication is to enlighten the reader regarding these differences and to underscore the fact that with all these differences taken into consideration, the Muslims remain as one umma, nation, which has to remain united especially in the light of the momentous challenges facing it from within and without. The rise of extremism and fanaticism, which has been fueled and funded by Wahhabism, has resulted in the loss of many lives of Muslims and non-Muslims alike. Wahhabism has been feverishly propagating for one of these branches of the faith while constantly belittling and attacking the other. Islam calls for peaceful coexistence among all members of the human family regardless of their creeds and ways of worship, but this is not what is being advocated by the proponents of Wahhabism and Takfirism who actually are the ones behind the spread of the virus of global terrorism.