I just finished The Lamb’s Supper by Scott Hahn and A Biblical Walk Through the Mass by Edward Sri. In one of those books (can’t remember which, now, and I already took them back to the library) the author raises a fascinating, if subtle, point about the exchange “The Lord be with you. — And with your spirit.”
In short, this is more than just a churchy “Have a good day. — You too!” Every time someone in Scripture is charged with doing a hard/scary/impossible task, he recognizes his unworthiness and God says “Hey. I am with you. I got this.”
A recent post on Reddit’s /r/catholicism got me thinking about this again.
User qsv2100 writes:
“The Lord was with” Joseph in Genesis 39. He was put in charge of a prison and then he was put in charge of Egypt and saved the nation from famine.
“The Lord was with” Joshua (Joshua 6:27ff) and he conquered the Promised Land.
“The Lord was with” Samuel the prophet and the history of the nation of Israel was changed and David was annointed as king.
“The Lord was with” David (1 Samuel 18:14ff) and he conquered many trials and ruled long as king.
“The Lord was with” Jehoshaphat (2 Chronicles 17:3 ff) and the Lord made the kingdom secure as it turned away from idol worship.
“The Lord was with” the Church at Antioch and a great number believed and turned to the Lord (Acts 11:21).
The angel declared that “the Lord was with” the Virgin Mary and also declared that she was “full of grace”.
When the Lord was with someone, then people have been empowered and important things have happened.
In the context of the Mass, this dialogue is a recognition of the great miracle about to take place, and a call to the Holy Spirit who dwells in the priest in a special way, asking Him to take on what is otherwise impossible.