Psalm 100 is chosen as a response to the Ezekiel reading, both using the imagery of shepherd and sheep.
Psalm 100 begins by commanding us to worship the Lord, appropriate to a day when we celebrate the reign of Christ.
"Enter his gates," that is, step away from the world that has been profaned, and step into a place of worship, a place in which we can experience the presence of the Lord.
Christians can on this Sunday obey these commands. We can step away from the ills of last year and begin our new year recognizing the steadfast love and faithfulness of our Lord.
Lectio Divina: Psalm 100