The story of Jesus and Nicodemus is preceded by a notice locating Jesus in Jerusalem
for the festival of Passover (v 23), continuing the spatial and temporal framework
announced in v 13. The framing is probably the work of the evangelist.
Although there are Synoptic accounts of dialogues between Jesus and religious
leaders in Jerusalem, there is no account in canonical sources of a private conversation
with a single leader. The dramatic encounter is probably the work of the evangelist, but
what follows the encounter itself seems to introduce other voices.
A key exegetical problem with these verses is where the direct discourse of Jesus
ends, since nothing marks its formal conclusion until v 21. Nonetheless, the clear self
references by Jesus end with v 12 and the basic story of the encounter of Jesus and
Nicodemus could well have concluded there. By v 16 the text is commenting on Jesus in
the third person. The comments appear reflective and treat Jesus as an object of
reverential belief. They thus appear to be the voice of the narrator. Vv 13–15 constitute
the core of the problem. Here the text speaks about the Son of Man in the third person.
Whether or not it was an authentic usage of Jesus, this way of having Jesus refer to
himself is a fixed part of the Synoptic tradition and was no doubt in the source material
available to the evangelist. At the very least, v 13 can be reasonably construed as part of
the discourse of Jesus. Vv 14 and 15, which clearly belong together as one sense unit,
offer a further comment on the Son of Man, relating to his passion. The motif of the
“lifting up” will reappear in a comment of Jesus at 12:32. The crowds then respond
(12:34) to the comment by asking Jesus why he speaks of the lifting up of the Son of
Man, a comment only intelligible in the light of 3:14, where Jesus had so spoken. At
some stage in the development of the Gospel, therefore, 3:14–15 were construed as a
comment of Jesus. The narrator’s commentary on the discourse then begins in v 16 and
continue through v 21.
The whole passage then seems to involve at least two stages of development, (1) the
basic story of Jesus and Nicodemus (3:1–12). (2) There follows an extension of that story
that incorporates and transforms a traditional saying about Jesus as Son of Man. At this
point Jesus is still speaking, not so much to Nicodemus but to the reader (vv 13–15). (3)
The narrator then intervenes with further reflections on theological issues posed by the
belief in Jesus as the one sent by God (16–21).