Bart Ehrman's often unnecessary and unqualified provocations within his texts do get tediously annoying. You can read his texts whereby he continually drops unqualified statements and just sit there wondering...we get it, Bart. We get it, you don't like Christianity.
Reading the intro to Lost Christianities (or the vast majority of his more popular books such as Misquoting Jesus, God's Problem or Jesus, Interrupted) is a great case in point. It begins in conspiratorial styled nature - we have an unknown "they" destroying alternative forms of 'Christianities'. He makes no historical mention of Christianity starting off as one rather unified belief - a Jewish movement believing Jesus to be the promised Messiah (as was preached by the Jerusalem Church as well as Paul to the Gentile Churches). This is played down to, well, no mention at all - and we hear of later Christian diversity as if they all existed in the beginning. The facts of the matter, as Ehrman has admitted to in numerous places, is that the New Testament documents are the earliest Christian documents we have - although there is some diversity (cf. Dunn's Unity and Diversity in the New Testament) we have a clear orthodoxy - the same orthodoxy that dominated the Church scene at its core to this day. Yes, we have diversity both ancient and current - but do tell me how this is analogous to the disputes of the orthodox apologists and the Gnostics.
But, alas, all later diversity is apparently equal despite the incomprehensible historical argument that Jesus was a Gnostic or a Marcionite. I see this book as the equivalent of a Fundamentalist Christian author claiming there were no later various forms of Christianity - both this fictional individual as well as Ehrman ignore the evidence and selectively present something the layman would most likely uncritically accept as scholarly.
His inconsistencies are amazing - just as amazing if you were to compare his book on the Da Vinci Code and Jesus Interrupted on the 'divinity of Christ' issue. He tells us that other versions of Acts were written "early in the church" yet a few pages earlier he gives all the alternative versions a late 2nd century date - around 100 or so years after canonical Acts.
He makes the issue of canon purely arbitrary - something greatly contradicted by his mentor the late Bruce Metzger in The Canon of the New Testament.
The list would go on, and on, forever and a day but I feel a tad better now!