There are many good texts on Christian history - these happen to be my favorite authors and texts for the first few centuries.

Recommended Texts
Rise of Christianity, by W.H.C. Frend. This is the text I recommend most - around 1,000 pages covering the first 600 years of Christian history. It is not a text that you expect to sit and read completely through - rather, it will serve as an outstanding reference book when you want/need to learn about a particular subject...like the Council of Nicea!

The Early Church, by Henry Chadwick. This is an excellent, yet less intimidating text on early church history. Chadwick was a premier British scholar and a great writer.

Men and Movements in the Primitive Church: Studies in Early Non-Pauline Christianity, by F.F. Bruce. One of my favorite scholars, this little text (a mere 159 pages) is simply power-packed with scholarship and significant implications in the study of early christianity and the New Testament.

Retrieving the Tradition and Renewing Evangelicalism by D.H. Williams
(Read my review of this excellent Williams text)

Pagans and Christians, by Robin Lane Fox.

A History of the Early Church, Vol.1-4 by Hans Lietzmann (English translation by Bertram Woolf).
(Read my review of Lietzmann)

Two Radio Interviews on Constantine
Listen to a pair of interviews I did with Keith Giles, a home church pastor.
Find links to these Radio Interviews on Constantine and click on the "Play" button at the top of the page.

Blog Articles by R.A. Baker
"Western" Individualism in the Christian Faith (4 Parts)
Part 1: Personal Forgiveness in the New Testament
Part 2: "Second Repentance" in the 2nd-3rd Centuries
Part 3: The First Monks and Hermits - 4th-5th Centuries
Part 4: Dietrich Bonhoeffer: Life in Community AND Life Alone
How Can a God of Love Also Have Wrath? (4 Parts)
Introduction: The Lamb of God in Revelation
Part 2: The Words of Jesus and the Apostolic Letters
Part 3: The Apostolic Fathers Documents (2nd century)
Part 4: The God of Love and Wrath: Apostles' Creed (4th century)
The Role of Women in Early Christianity (5 Part Series)
The Chosen Helped Me "See" the Women Around Jesus
The Women Who Followed Jesus
Women in the Orbit of the Apostle Paul
Women shall remain silent?...Difficult verses in Paul's Letters
Women in Problematic 2nd Century Sects

Articles and Papers by R.A. Baker
How the New Testament Canon was Formed
The Development of the Trinity in the New Testament
Review of Bart Ehrman's Lost Christianities
An Introduction to Gnostic Texts
An Introduction to "The Sayings of the Desert Fathers"
"Second Repentance" in the Early Church: The Influence of The Shepherd of Hermas
Wine in the Ancient World
Wine in the Ancient World, Part 2 (unfinished)
The Da Vinci Code: Fact, Fiction, or Faith?