Christadelphians affirm the virgin birth of Jesus as a historical fact recorded in Scripture. Mary was a virgin when she conceived Jesus through the direct action of God's power (the Holy Spirit, understood as God's power). This miraculous conception is what makes Jesus the 'Son of God' — he had no human father, only a human mother. The Father is his divine progenitor and the source of his unique nature.

The virgin birth is important in Christadelphian theology for establishing Jesus' unique identity as the Son of God. Because he had no human father, he was not subject to the ordinary mechanisms of human generation — though Christadelphians do teach that he inherited a mortal, sinful nature from his mother Mary. The absence of a human father distinguished his origin and made possible his unique relationship with God.

The Christadelphian reading of the virgin birth does not entail the pre-existence of the Son: the conception was not the 'taking on of human flesh' by a pre-existent divine being (as in mainstream Christology) but rather the miraculous creation of a new human being in Mary's womb by the power of God. Jesus began to exist at his conception; before that, he existed only as the plan or purpose of God.