The Philidelphia Confession of Faith Very similar to the 1689 London Baptist confession. A decent representation of the beliefs of the web admins.
Keach's Catechism This is usually the one packaged with the 1689, and sometimes called “The Baptist Catechism.”
The Glory of a True Church by Benjamin Keach. Discusses church politic, duties of members, church discipline.
A Declaration of the Faith and Practice of the Church of Christ in Carter Lane, Southwark A covenant and confession used by John Gill's church.
A Complete Body of Practical Divinity See Book 2, Chapter 1 (page 615 in the EPUB file) for the section, “Of the Nature of a Gospel Church…” and Book 2, Chapter 2 (page 642 in the EPUB version) for the section titled, “Of the Duties of the Member of a Church to Each Other.” Or, check out this PDF: External Worship, as Public by John Gill
Duties of Christian Fellowship by John Owen An excellent study guide for church members. Contains full-text scripture references and discussion questions.
Gospel Baptism by John Gill A notable book on the subject.
A Treatise Concerning The Lawfull Subject of Baptism by John Spilsbery
The Everlasting Covenant by Benjamin Keach A sermon on the covenant of Grace.
A Discourse on the Covenants by Nehemiah Coxe Discusses the Noahic Covenant, the Covenant of Circumcision, the Ademic Covenant, and the Covenant of Grace, and other topics.
The Display of Glorious Grace by Benjamin Keach “The Covenant of Peace, opened in fourteen sermons…in which the Errors of the present Day, about Reconciliation and Justification, are Detected.”
The Divine Covenants by A. W. Pink Discusses the Everlasting, Adamic, Noahic, Abramhamic, Sinaitic, Davidic, and Messianic, covenants; part eight concerns the Covenant Allegory, wherein Galatians chapter 4 is discussed.