Exactly so, and this is my attitude about it as well. I quoted it in response to Blogger's question, why anyone would marry a girl he did not intend to have sex with. I was fully aware that the next thing Blogger would do is forget his own question and thump the table with allegations of forgery.
I wasn't the first one who used the term forgery. I don't believe it is Scriptural.
As far as it being a recording of what someone believed were the beliefs of early Christians, the Muslims believe that we believe that Mary is a member of the Trinity (I can't remember which one falls off, Son or Holy Spirit). Again, this is not evidence that this is an early Christian belief. Adopted later? Yes. But there is no evidence the earliest believers thought about Mary in this manner.