Many years back we had a few requests (and one defiant challenge) to look into the work of Karen Armstrong, author of several books including one we will survey in part here titled The History of God. Since that time, around 2001, we have had no request at all about her work, and she seems to now be a more obscure figure. However, it seems best to maintain and update this critique for the record.
When reading Armstrong, do not expect any original research or argumentation. The findings of liberal Biblical scholarship and of the likes of the Jesus Seminar are taken as indisputable fact, and the commentary progresses from there. Thus for example Armstrong dates Proverbs to the 3rd century BC without explanation or analysis, much less dealing with of competing views.
In light of that most or all of what Armstrong assumes to be true about the Bible is refuted by material on this site, we merely refer readers to our indices (see sidebar) and offer a sample of Armstrong's failed claims:
It is clear from her introductory words that Armstrong grew up in a religiously strict environment and desired a more personalized religion, but is upset because she didn't experience God the way she wanted. This is hardly a rational basis for analysis.
Armstrong says such things as this often of the Bible: "These myths were not intended to be taken literally, but were metaphorical attempts to describe a reality that was too complex and elusive to express any other way." 
But how does Armstrong know this? How does she know that Exodus or Enuma Elish were "not intended to be taken literally"? Has she interviewed any ancient people and asked? Of course not -- it is merely assumed that there was some unknown "too complex and elusive" reality that these authors were trying to describe.
Recounting the salvation history of the Bible and the atonement, Armstrong says, "there must have been an easier and more direct way to redeem mankind." 
If there was, Armstrong does not lay it out; she merely looks at the present scenario, says, "God could have done better" and leaves it at that.
At the back of such objections lies a presumption, "I know better than God and could have done it better." Really? Does any person has the capacity to lay out a perfect alternate history and know there was a "better way"? Not even Harry Turtledove claims that kind of genius.
Put it this way: It's like those who say Abraham was a bad choice for God to make -- really? So who do they know who was a better choice? Do they have a list of names from the 18th century BC along with full resumes and character references? Such objections assume to possess omniscience in the service of declaring that omniscience did a poor job.
The Trinity is a top subject for Armstrong. Though she knows about the Wisdom literature, she doesn't see the application to the Trinity, which she assumes is the product of Nicaea, along with the divinity of Jesus. (See link below.)
The Trinity, she says, "only makes sense as a mystical or spiritual experience" , which is an "only" without recourse to the relevant literature: The Trinity makes sense in light of the Wisdom tradition, and "experience" is unnecessary to understand it.
We are advised that Arius, the defender of the heretical view that Jesus was a created being and not eternal divinity, "passionately believed" what he taught, while Athanasius, who taught the eternal divinity of Christ, "managed to impose his theology" on others and was an unhappy camper.
This seems rather obvious favoritism. Why is it that those who "passionately believe" what is wrong are just fine? Does passion make error of no moment?
We are told that it was only at the end of the 2nd century that Christianity gained any converts intelligent enough to articulate its views .
Apparently Armstrong has not read Wayne Meeks' The First Urban Christians showing that Paul had more than the usual expected number of converts from the wealthy/literate Roman upper and middle class. She also doesn't read about the Romans, who she says had not "inherited the Greek hostility to Jews."
Indeed? Tacitus, Celsus, and Lucian, and other Romans who referred to the Jews in derogatory terms apparently didn't receive that news.
The ancient pagans did not worship idols, we are told; the idols were "a focus that had helped people to concentrate on the transcendental element of human life." 
Indeed. I am sure "transcendental elements of human life" is what the Canaanites had in mind when they sacrificed infants and had sex on the altars. Armstrong is only half right, however: the idols were intended to be focal points for the gods depicted to come down and be present.
Armstrong tells us that prophets who condemned false religion were doing so because they were full of insecurities, secretly knowing that their own god was as made up as that of others .
Armstrong uses JEDP parsing as a basis for some arguments. This is a theory which Armstrong admits has been seriously disputed, but which she uses anyway, because no one has come up with anything better.
Things like the denunciation of the Pharisees are declared "inauthentic" because they are offensive. (There is no conception of the ancient use of riposte.)
See here on Wisdom literature.
In sum, Armstrong is singularly unimpressive as a source, both in terms of logic and in terms of scholarly acumen.