Sojourner, I think there are many scholars who attest that there was a good chance these authors were authentic, unlike the Gnostics that were written much later during the 2nd Century. The fact that there is consensus that Paul wrote the Epistles earlier than the Gospels provides another credible attestation to the Christian doctrine as it relates to Jesus Christ.
Actually, scholars, for the most part, agree that we don't know who wrote the Gospels. We have evidence of the titles and authorship being added at later dates. We have evidence that they were being circulated first as anonymous. Even which John supposedly authored the Gospel of John was debated for quite some time.
Also, scholars are now beginning to think that parts of the Gospel of Thomas, the earliest layers, come from the 60's C.E. This predates the Gospel of Mark. So some of the gnostic texts are being considered somewhat historical, and most are considered important as to understand Christianity and how it developed.
As for Paul, there is a consensus that he wrote some of the Epistles. We know some of the writings accredited to Paul were never written by him. We have 7 authentic letters of Paul. The rest are debated and most are thought to be written by others, probably after Paul's death. However, they don't attest to much. They talk very little about Jesus. They give little detail about the life of Jesus. They mention nothing about a supposed virgin birth or the miracles of Jesus.
They do tell us he had a brother, that he was crucified, and supposedly resurrected. However, there is one catch. Paul stated very clearly that the resurrection of Jesus signified the beginning of the general resurrection (you must understand the eschatological apocalyptic ideas of the Jews during that time). Paul stated that unless the general resurrection happened, the resurrection of Jesus never happened. They both were true or false. If Jesus was resurrected, then the general resurrection had to occur within a short time. If the general resurrection wasn't going on, the Jesus was not resurrected. According to Paul, you couldn't have one without the other. Paul died, the general resurrection never happened, and it gives us less reason to believe Jesus was resurrected.
Just to finish off. The books are only semi-historical. They are under the genre of lives. They contained myths, as was common. At the same time, they contained theological messages that were geared to certain groups. The Gospels don't even agree in all parts, and have historical inaccuracies as apart of them. Thus, scholars, by far, agree that they are not 100% accurate and can not be treated as such.