Craig Evans, Joel Green and others have noticed a series of remarkable parallels between the births of John (the Baptist) and Jesus, as recorded in Luke 1.

• In both cases, the conception was unexpected, Lk 1:7; 1:26f, and is announced by the angel Gabriel, Lk 1:11-19, 26-38.
• Both future parents are ‘troubled’, Lk 1:12, 29, but are told not to be afraid, Lk 1:13, 30.
• Both are promised a son, Lk 1:13, 31, and are given names for their unborn offspring, Lk 1:13, 31.
• Both sons will be ‘great’, Lk 1:15, 32.
• Both parents ask, ‘How?’, Lk 1:18, 34.
• Both are given signs, Lk 1:20; 1:36.
• There is joy over the birth of each son, Lk 1:58; 2:15-18.
• At the respective circumcisions, God is recognised as having been at work, Lk 1:59-66; 2:21-38.
• On both occasions canticles are sung, Lk 1:66-78; 2:29-32.
• Both sons ‘grew and become strong’, Lk 1:80; 2:40.

But there are important differences, too.  As summarised by Ian Paul:

• Zechariah is to become John’s father, by the natural human method of sexual intercourse, but Mary is to become mother by miraculous intervention.
• John is born to aged parents, as the answer to their own prayer in the light of their need. Jesus is born to a young virgin, out of the need of Israel, not Mary herself, who is taken by surprise.
• John will prepare the way for the coming one, as ‘prophet of the Most High’, but Jesus will be called ‘Son of the Most High’ and ‘will reign over the house of Jacob forever’.

Luke wants us to know that

• John and Jesus are ‘twin agents of God’s salvation’.  Their stories overlap in several ways.  For instance, Lk 1:39-56 tells us that Mary and Elizabeth are relatives, and the former visits the latter.
• John is Jesus’ forerunner, in every respect and from conception onwards.
• Jesus is superior to John in every respect.  John’s birth is unusual; Jesus’ is altogether unique.  John will be ‘great’ before the Lord, Lk 1:15; Jesus will be called Lord, Lk 2:11.

Andrew Lincoln refers to this last feature ‘step-parallelism’, in which the second element is always the greater.  We would expect, then, to find that the conception of John, wonderful though it was, given the ages of his parents, would be surpassed in wonder by that of Jesus: obviously, this leaves room for a virginal conception, given that for a young woman to conceive by natural means would be less wonderful than for an elderly woman to conceive.