Our conclusion from this survey is, therefore, that we have found nothing to upset the verdict, to which we have been led by critical investigation of the Acts of the the second and third Gospels, as well as the Acts, were composed while St. Paul was still alive, and that the first gospel came into being only a few years earlier. - Adolf Harnack
Carl Gustav Adolf von Harnack (7 May 1851 – 10 June 1930) was a German Lutheran theologian and prominent church historian. He produced many religious publications from 1873 to 1912 (in which he is sometimes credited as Adolf Harnack).
Harnack traced the influence of Hellenistic philosophy on early Christian writing and called on Christians to question the authenticity of doctrines that arose in the early Christian church. He rejected the historicity of the Gospel of John in favor of the Synoptic Gospels, criticized the Apostles' Creed, and promoted the Social Gospel.