Ecclesiology: Message; Mission; and Unity of the Church; is the result of the work of Adventists theologians who together have been exploring the biblical understanding of the nature and mission of the church. We have been told that “the church of Christ; enfeebled and defective as it may be; is the only object on earth on which He bestows His supreme regard” (TM 15). This being the case it is incumbent on church members to gain a sound biblical understanding of the nature of that on which Christ “bestows His supreme regard.” It is this deep concern of Christ for His church that led the Biblical Research Institute of the General Conference; in conjunction with the Biblical Research Institute Committee; to initiate a series of studies on the nature and function of the church. The first volume of a projected three volume set was published in 2009 (Toward a Theology of the Remnant: An Adventist Ecclesiological Perspective) and now we bring to our readers this second volume. It deals with extremely relevant topics such as the unity of the church and its message and mission. We do not only look at biblical material but also at post-apostolic developments in order to place Adventists ecclesiology within the flow of Christian history as God’s end-time remnant. Any pastor; teacher; leader; and church member who; like Christ; has a high regard for the church will benefit from reading this volume. It will provide for the readers a better comprehension of the Adventist movement and will hopefully inspire us to contribute to the unity of the church; to gain a better understanding of its message; and to be involved in its mission. We pray this study will be a blessing for the church as it reflects on itself.