In studying the Lord’s Prayer we tend to focus on the actual content of the prayer that Jesus taught us. Little attention is paid to the audience who listened to this teaching. In fact, in the account in Luke, the Lord’s Prayer was explicitly a public answer to a disciple’s request, “Lord, teach us to pray, just as John taught his disciples.” It is a mass whom Jesus was addressing. Not an individual. It wasplural. Hence Jesus’ example of prayer contains plurals: our Father, give us, forgive us, lead us not into temptation, deliver us …
The prayer is meant to be prayed as a group, not individually.
So then, at the point when Jesus taught the people to pray to the same Father, “forgive us our debts, as we also have forgiven our debtors” (Mt. 6:12, or Lk. 11:4, “Forgive us our sins, for we also forgive everyone who sins against us”), it was perhaps a very awkward moment. It was the awkward moment when the adversaries or enemies within the mass of people listening to Jesus would suddenly think, “Oh! We cannot pray this without mutually agreeing that we forgive each other.”
The prayer cannot be prayed without adversaries explicitly stating in unison that they have forgiven each other. The prayer itself is the declaration of forgiveness towards each other.
“Oh, my adversary in the crowd knows I am praying this! That means …”
In a sense, each adversary in praying the prayer is also asking the Father to forgive the other.
In Matthew, the conclusion of the Lord’s Prayer was precisely, “if you forgive other people when they sin against you, your heavenly Father will also forgive you. But if you do not forgive others their sins, your Father will not forgive your sins” (Mt. 6:14-15). Hence there is no point praying at all. So if adversaries sincerely pray the Lord’s Prayer together, they are then forgiving each other, and their Father will answer to this prayer to forgive them.