I always have mixed feelings when I read books by Bart Ehrman. He is a respected scholar and he is a gifted communicator. Those things don’t always go together. However, his books are also often heavily shaped by his reaction to his former evangelical faith.
This is true for The Triumph of Christianity as well. Ehrman claims that he is writing this not to celebrate or to mourn the victory of Christianity. He is simply telling the story as impartially as possible.
There are plenty of good things in the book. The concept of the book is important, as the dramatic rise of Christianity over a few centuries does call for an explanation.
I like the work Ehrman does in explaining the process of conversion and how that looked different from the decision to adhere to other contemporary religions.
Ehrman rightfully contrasts the henotheism of other religions with the monotheism of Christianity. No other religion (except perhaps Judaism) could have taken over the Roman Empire. Henotheists may primarily worship one god but do not deny the existence or the importance of worshiping other gods. Only Christianity lifted one God to the full exclusion of other gods.
What I didn’t like is that Ehrman is still reacting to his former faith. He seems to enjoy reminding evangelicals that history didn’t happen the way they normally assume it did. He gets little digs here and there toward those with a more traditional understanding of the rise of Christianity.
That is a matter of style. What I dislike more is that he is overly skeptical of Christian sources. I’m all for a critical reading of sources but that is different than a skeptical reading. He seems to assume that most often Christians are seeking to deceive unless their claims can be supported by their opponents.
As someone who has studied history outside of biblical and religious areas, I have noticed that other historians are less skeptical of their sources. They often give them the benefit of the doubt unless there are other historical readings to question them.
I understand that much of Ehrman’s audience is of the agnostic/atheist persuasion and so skepticism toward all things Christians is part of the package.
There are some good things in The Triumph of Christianity but I would suggest reading it along other authors as well.