The thesis argues that the most distinctive feature of the Labour Church was Theological Socialism. For its founder, John Trevor, Theological Socialism was the literal Religion of Socialism, a post-Christian prophecy announcing the dawn of a new utopian era explained in terms of the Kingdom of God on earth; for members of the Labour Church, who are referred to throughout the thesis as Theological Socialists, Theological Socialism was an inclusive message about God working through the Labour movement. By focussing on Theological Socialism the thesis challenges the historiography and reappraises the significance of the Labour Church. Theological Socialism is examined from different vantage points: the social and ideological setting of the Labour Church in late nineteenth and early twentieth century Britain; the events and concepts which shaped John Trevor’s religious and political thinking; the motivations and aspirations of the Theological Socialists who aligned themselves with the movement, arguing that they were a particular group within Ethical Socialism; and the issues and concerns of the Labour Church in Birmingham, a contextual study which refutes the commonly held understanding about the lifespan of the Labour Church as a movement. The thesis concludes highlighting a continuing theological imperative for the British Labour movement.