Following are some observations on the curious account of the birth of Jesus which a careful study of the Gospels reveal:
In John 8:31 ff., there is a debate between Jesus and the Jews about their descent from Abraham, who is characterized as their father. In verse 39, Jesus calls into question the legitimacy of their birth from Abraham and in verses 41-44 he begins to point sarcastically to the devil as their real father. To this the Jews respond: “We were not born illegitimate. We have but one father, God himself.” The latter clause (“We have but one father, God himself”) is their response to the latter charge of Jesus that they were the devil’s progeny.
Now the point, which requires attention, is that in the very next response by the Jews, they doubt the legitimacy of Jesus’ birth: “Aren’t we right in saying that you are a Samaritan and demon-possessed?” (verse 48). This is another way of saying: “Look, our birth is not illegitimate; Yours is. We were saying all along that your mother had relations with a Samaritan before your birth.” Curiously enough, “John” does not make Jesus deny this particular portion of their charge. (i.e., in verses 49 f., Jesus denies being demon-possessed, but does not say anything about the first portion of their charge about his illegitimacy of birth). This clearly indicates that John acknowledged that the Jews had serious doubts from the beginning about the birth of Jesus and his unwillingness to quote any response by Jesus, to deny this charge, proves that John acknowledged that Jesus’ legitimacy of birth was disputed.
Furthermore, a whole bunch of scholars, the most notable of them perhaps being Adolf von Harnack