It seems that persecution is not an appropriate subject of discussion in the time of 'no' persecution. Looking back over the history of Christianity, however, one finds that persecution has been one of the main concerns for all times. Persecution for cause of personal conviction and practice has been a dark side of human history, whether religious or political. That the religion whose main teaching is 'to love God' and 'to love others' has been a protagonist of 'hating and hurting others' in history must be blasphemous to its God and hypocritical to humanity. Baptists have been more the persecuted than persecutors in their history. Baptists were from the beginning the persecuted. Just as Anabaptists in sixteenth-century were persecuted by both Catholics and Protestants, Baptists were persecuted by both the then established church, the Church of England, and reforming Puritans. They have shaped their convictions, theology, and way of life through dealing with persecution, including the concept of religious liberty and separation of church and state. Roger Williams initiated the movement of religious liberty in American history. From the very beginning of his life in America, he was driven to struggling for 'soul liberty' and building a 'wall of separation' between the church and the state. Persecution was always there as he fought through his activities and writings in Old England and New. Persecution was a negative experience that made Williams go beyond orthodox Puritanism and reach the idea of religious liberty and separation of church and state. This paper is an investigation as to how persecution had an effect on Williams's view of religious liberty and separation of church and state. Chapter one is introductory comments. Chapter two sketches Williams's life around persecution and the New England situation of the time. Chapter three deals with different perspectives on his view of persecution: biblical, historical, ecclesiastical, and civil. Chapter four is implication and conclusion.