I get asked a lot about how to get started studying church history. These are the books I recommend. Also see How to Study Christian History, which gives a plan for learning church history.
To get a quick introduction, here's an excellent starter package:
If you use the links on this page to purchase the books from Amazon, I get a small commission, which helps support this site.
The Ante-Nicene Fathers and specifically volume one and volume two. I cannot overemphasize how important these writings are. If you are going to read any Christian books outside the Bible, you ought to be reading these! These are the writings of those closest to the apostles. If you don't read these, you're just guessing at what the apostles taught the churches, and you're just hoping that you've joined the right church and interpreted the Bible correctly.
Amazon has these writings individually, as a set, and on Kindle.
A lot of people don't question their own interpretation of the Bible. That's sad. It's obvious that millions of Christians, all claiming to be led by the Spirit and honest in their interpretations, have come to many different interpretations of it.
They have then disobeyed and dishonored Christ by dividing over those interpretations, all the while claiming to be sound, spiritual interpreters of the Scripture.
We need guidance. God has promised to reveal truth to the church (1 Tim. 3:15; 1 Jn. 2:27, where each "you" is plural), not to individuals (Heb. 3:13; Eph. 4:13-16; 1 Cor. 12:19-21). From Christian history, you learn what churches throughout the ages believed, and the results they got from their beliefs in joy, unity, and holiness.
It is in this way and not by our own confident interpretations of Scripture that Jesus said to know truth (cf. Matt. 7:14-20 and Jn. 5:39-40).