Below is a link to a nice review on the importance of historical theology. In Evangelical Circles (Baptist, Anabaptist, Conservative Evangelical,Pentecostal, Charismatic, etc.) there is a huge lack of historical theology. We tend often to fall into the trap of some other groups (Jehovah’s Witness, Mormon, etc.) that try to connect themselves with the NT church and then ignore the next 1500, 1700, 1900 years of church history.
To truly understand who we are we need to see the Christian Faith through understanding God’s work in history. After all, a defining characteristic of the Christian (and Jewish) faith is the recognition of God working in history. That history does not stop in 95AD.
Of course, if Historical Theology is worthwhile to see God’s work in history, one should study Historical Missions Theology since it is equally important to see the Missio Dei in history.
Here is the article: Why study historical theology.