As we have seen, the angel has made some startling promises concerning the child to be born - promises that cannot be fulfilled if Joseph is to be the father.
Gabriel's response to Mary's question "How can this be seeing I don't know a man?" can be considered in two parts. The first of these is:
"...The Holy Spirit shall come upon thee and the POWER of the Most High shall overshadow thee."
In effect, Gabriel tells Mary that God will take care of everything...a way will be found...she will be protected. Then:
"And Elizabeth thy kinswoman, she has also conceived a son in her old age, and this is the sixth month with her that was called barren. For no word from God shall be void of POWER." (1:36-37)
Elizabeth was old, she was barren, yet she had conceived a child through the POWER of YHWH.
If the Power of YHWH can perform this great work, he tells her, then how simple is the much lesser task of finding an appropriate father for your child.
Gabriel's response to be continued in Part 5...