Historical theology is a branch of theology that investigates the socio-historical and cultural mechanisms that give rise to theological ideas, statements, and systems. Research and method in this field focus on the relationship between theology and context as well as the major theological influences upon the figures and topics studied. Historical theologians are thus concerned with the historical development of theology.
Historical Theology has (in fact) many different definitions. It often refers to the development of Dogma or of the chronological study of the doctrines of the Christian Church. Christian Doctrine has not grown Systematically. Theology, Systematic, Biblical or Historical (among a few of the perspectives), only serves as a resource for obtaining a better perspective of that which is outlined in God's Word. Consider the parable of our Saviour in Matthew 13.; or Luke's contribution through the Spirit authored history - the Acts of the Apostles and John's 'Book" of the Revelation of Jesus Christ - as in chapters two and three. All of this Scriptural form of history - Biblical, prohetic, Historical joins to reveal the genuinely obvious usefulness of the study of the Scriptures ..."along with" any added studies of the church, its doctrinal understandings and its spiritual walk and growth.
Studying the source materials - for example: the letters and commentaries of those involved in "making" history is absolutely vital! How we, as believers, think of the Truth of Scripture or its doctrinal content - in the light of the history of theology and the church ... can change our understanding of the will of God. In fact, our view of God Himself can come under the major influence of both good and dangerous historical forces. Our own spiritual well-being can be enhanced or revearsed due to our understanding or ignorance of the historical development and/or the historical regressions of the church's understanding of the Truth, as God's Holy Word.
Simply stated: Systematic Theology is designed to be topical and logical, and Historic Theology is meant to be chronological and philosophical. Whatever historical theology is, it is far more than the "study of the interpretation of Scripture and the formulation of doctrine by the church of the past.” (Allison) If we decide to study "historical theology" we are not simply looking at the church, doctrinal or creedal statements and those forces' impact on the history of the church. The church, rather, needs to be seen as progressing or regressing or possibly (?) becoming dormant for a period. The reality of Historical Theology is that it is not just a study of Christianity Worldwide but should be studied regionally, geographically, biographically and then chronologically, with some real awarenes of all of this date and detail - held as context ... at one time.
Historical theology will give nothing more than perspective and any effort to make more of its 'facts' revealed will inevitably lead to bias, provincialism. The ability to distinguish truth from heresy is a matter of prayer, the Holy Spirit and the resulting insight that comes from exegetical study of God's Word. In other words it will give us the opinions of relatively biased author's viewpoints and opinions or even personl insights regarding what is soundly orthodoxy or what might be 'rightfully' understood as heresy. The idea of a truly "objective historian" is a most amazing idea... in that it is simply unrelated to anything that even slight tastes of reality. The historian collects and by his means of collection he or she interprets.
Ephesians 3:14 "For this cause I bow my knees unto the Father of our Lord Jesus Christ, 15 Of whom the whole family in heaven and earth is named, 16 That he would grant you, according to the riches of his glory, to be strengthened with might by his Spirit in the inner man; 17 That Christ may dwell in your hearts by faith; that ye, being rooted and grounded in love, 18 May be able to comprehend with all saints what is the breadth, and length, and depth, and height; 19 And to know the love of Christ, which passeth knowledge, that ye might be filled with all the fulness of God."
Historical Theology or the History of Dogma can do little more than share the variations in biblical interpretation and it can do nothing more than summarise the formation processes of the historic creedal outcomes produced in synods, counsels and confessions. The biographical and chronological nature of Historical Theology is meant to place faces and personalities and human tensions with the rise and fall of Christian history and it should not be expected to accomplish more. To imply that Historical Theology as 'chronica' can do anything similar to the biographical truth taught in the lives of Israel's Fathers or Kings or Prophets is absurd. The Word of God is more clearly the Word of God whenever compared to the paltry efforts of Historical Theology's biographical efforts.
Historical Theology or the history of Dogmatic Theology can either protects and promote the various views of this or that denomination or it can reveal the failures of the same. Historical Theology offers the church of Jesus Christ the ability to understand the historical compromises that can reveal the weaknesses in its denominational beliefs. The research into the modern church's history (or the philosophical history and political forces behind these modern ideas) should assist the sincere and dedicated student in identifying the fundamentals errors and strengths in various periods, geographic regions or systems of thought that might have developed.
The question of the overshadowing power of God - of the sovereign and providential acts of God in history should be addressed and may be understood from the study of Christian history. The idea behind "good history" is usually the idea of collecting and collating theology throughout those periods of natural secular historical developments. The idea that one aspect of doctrine can be developed in and of itself with only some minor attention to a balanced chronological methodology will fail to address the underlying forces for good and evil behind its development within the whole of the reality of history.
The goals of a strong and useful Historical Theology should include addressing the Word of God at the various normal chronological and geographical junctions. The history makers must be studied as sourced from their own writings rather than that of their enemies alone. The shifts in the sands of belief need to be understood, not just identified and the central truths of eschatology, ecclesiology should not be given second place to theology since history has often been influenced by one as much as the other. 
- Blackwell, Marc S. "Dr.". Historian. Cape of Good Hope Publishers. Retrieved 11 June 2013.
- Finlayson, R. A. The Story of Theology. Second ed. London: Tyndale Press, 1969. 70 p. SBN 85111-029-0
- Richardson, Alan. Creeds in the Making: a Short Introduction to the History of Christian Doctrine. Reissued. London: S.C.M. Press, 1979, cop. 1935. 128 p. SBN 334-00264-8 pbk
- Doctoral Study in Historical Theology at Saint Louis University