But Mary is not the only one who rejoices.
As the Rev. Dr. J. Clinton McCann Jr., professor of biblical interpretation at Eden Theological Seminary, sees it, all who are "motivated and equipped to do God's will by the spirit-filled 'me' of Isaiah 61:1 also 'greatly rejoice in God' (Isaiah 61:10).... The source of their joy is their participation in the fulfillment of God's purposes for human life."
Dr. McCann continues: "Mary goes on to affirm that 'the Mighty One has done great things for me' (Luke 1:49). As her song unfolds, however, these 'great things' are clearly *not just for her.* Rather, they are for 'the lowly' (v. 52) and 'the hungry' (v. 53)."
"Mary rejoices because God's work is being done, and because she has become a participant in the working out of God's will in and for the world."
As Dr. McCann notes, the refrain in Shirley E. Murray's hymn, "For Everyone Born" announces that 'God will delight' as well. And no wonder! How could God refrain from rejoicing when "people join in the holy work of creating justice and joy"!
Professor J. Clinton McCann Jr.'s full reflections on Luke 1:46b-55 can be found in Connections: A Lectionary Commentary, Year B, Volume One, 2020, pages 282-283.