The Gospel of Matthew reports that Pilate's wife said to him, "Have thou nothing to do with that just man; for I have suffered many things this day in a dream because of him" (Matthew 27:19). This report may have found its way into the Gospels from a variety of different channels such as rumor, legend, or secondhand testimony. Some early Christians proposed that this report represents firsthand knowledge on the part of the evangelist; and therefore Pilate's wife, or even Pilate himself must have converted to the gospel of Jesus Christ.
The tradition of Pilate converting to Christianity has a complicated history that begins in the latter half of the second century when Irenaeus (A.D. 130-200) and Tertullian (A.D. 160-220) reported that added knowledge could be found in extracanonical documents about Jesus' trial before Pilate and that Pilate had written personally to the emperor Tiberius about Jesus.
These passing references most likely find their origin in the pseudepigraphal Acts of Pilate. The Christian Acts of Pilate were most likely written in the second century as a counterbalance to the pagan Acts of Pilate that had been forged at the time of Maximin and that were being taught in schools as a refutation of Christian doctrines and claims. The Christian Acts of Pilate undermines the pagan forgery by reporting special knowledge about the details of Jesus' interrogation before Pilate, Pilate's secret inquiry of the chief priests after Jesus' crucifixion, and his private conversion to Christianity. The success of the Christian Acts of Pilate can be appreciated by the fact that they survived while the pagan Acts have been lost. Knowing the history of these documents inspires little confidence that they report any kernel of historical truth about Pilate's conversion to Christianity.