In Christianity and Islam, it is asserted that Jesus of Nazareth was conceived by his mother Mary solely through divine intervention and without sexual intercourse, thus resulting in his virgin birth. In accordance with these beliefs, Jesus had just one biological parent instead of the necessary two; Mary's husband Joseph was his father only in the legal sense. Most Christians hold that Mary's virginity was perpetual. Though not biologically related, Jesus being Joseph's adoptive son is cited as linking him to the Davidic line. The Christian understanding is that the birth of Jesus by a virgin woman was made possible by the Holy Spirit of the Trinity.