Some good points, in my opinion:
Benefits to be gained from the study of Church History
A. A perspective informed by a sense of continuity
1. The whole family in heaven and earth (Eph.3:14)
2. Connecting the canonical history with our own time (Acts 28ff)
3. Escape from the theological and ecclesiastical provincialism (1 Cor.14:36).
B. The encouragement of a Godly Heritage
1. The great cloud of witnesses (Heb.11; 12:1)
2. Perspective on persecution (James 5:10-11)
C. Learning from the mistakes of others (1 Cor.10:6-10)
1. A wise man learns from others’ mistakes, a fool must make his own.
2. Those who will not study history are doomed to repeat it.
From "Church History" by Steve Gregg