This study explores how internal schism blunted the sense of Christian unity at the Council of Chalcedon (451 AD). The subject was specially chosen in order to study the cause and nature of the schism among Christian brothers that created Chalcedonians and Non-Chalcedonians. Vital questions dealt in the study are about the possibility of achieving stable and constant Christian unity or reconciliation, resolving the spirit of hatred and enmity among Christian brothers and working towards the guarantee that all efforts of reconciliation are based upon truth and friendliness, without any attempt at proselytism. In this study the various theological, ecclesiological and political reasons for the schism between Chalcedonians and Non-Chalcedonians are explored. Moreover, this second chapter describes how Christians developed a spirit of hatred and enmity among themselves, which resulted in persecutions and murder of a great number of Christians by fellow Christians. It also illustrates how politicians and state authorities exploited these differences to persecute those Christians who did not support their particular viewpoints. It seems that the initiative of ecumenism is now acceptable to most Christians, though there still exists much mutual suspicion that is slowing the achievement of unity. Towards the end of the thesis some constructive recommendations are offered with the aim of facilitating Christian unity and reconciliation. We can no longer continue to hide or minimise differences, which has been the bane of the Churches in the past.