The “Amen”, which expresses the faithful’s adherence to what has just been proclaimed, concludes almost all Christian prayers, including the Our Father. However, when prayed within Holy Mass, the Lord’s Prayer does not end with this word.
Why is it omitted in this instance? It is because an embolism – an addition – immediately follows, which expands on the final phrase of the prayer: “deliver us from evil.” After announcing it, the celebrant, while keeping his hands extended, continues: “Deliver us, Lord, we pray, from every evil, graciously grant peace in our days, that, by the help of your mercy, we may be always free from sin and safe from all distress, as we await the blessed hope and the coming of our Saviour, Jesus Christ.” And the faithful reply with the ancient acclamation, used since the earliest times of the Church: “For the kingdom, the power and the glory are yours, now and forever'. (Taken from Heralds of the Gospel Magazine, August 2016)