This is one definition of ecclesology: the branch of theology concerned with the nature and the constitution and the functions of a church.
How should someone begin studying the nature, constitution, and functions of a church? I have found two distinct paths toward developing a biblical ecclesiology.
The first path begins with the contemporary church along with its nature and practices. The theologian then uses Scripture to justify the various roles, functions, and practices of the contemporary church. This method allows various theologians to justify different and divergent practices.
The second path begins with Scripture. The theologian examines the nature and practices of the NT church as recorded in the Bible. These “descriptions” are then used as “prescriptions” for comparisons to the contemporary church.
In 1 Corinthians, Paul encourages the church in Corinth to compare their practices to the practices of other churches (1 Cor 7:17; 11:16; 14:33-34; 16:1). We should compare our practices to those of the NT churches as well. We should not begin with our practices, then justify them with Scripture. We must begin with Scripture when we are developing our ecclesiology.