O merciful Lord, grant to your faithful people pardon and peace, that we may be cleansed from all our sins and serve you with a quiet mind; through Jesus Christ our Lord, who lives and reigns with you and the Holy Spirit, one God, now and for ever. Amen.
This collect is found in the 1662 Book of Common Prayer on the Twenty-First Sunday after the Trinity. It was appointed as a petition in Burial Office in the 1979 BCP and returned as a Sunday Collect in the 2019 BCP.
The brief prayer is instructive. Highlighting God’s mercy it calls on the Lord to grant us “pardon and peace.” The order here is not accidental for without pardon there can be no peace; neither peace with God nor with one another.
Next we see that just as the goal of pardon is “that we may be cleansed from all our sins, so the goal of peace is to “serve you with a quiet mind.” Thus while the world tells us that our goal is be to be happy, we are reminded that the goal of the Christian is faithful service.
But why service “with a quiet mind?” Because service that flows from other sources, such as guilt or manipulation or intimidation, forces us back into unhealthy servitude from which Christ came to set us free.
How do we attain a quiet mind? It begins by being pardoned and it continues as we realize just how merciful is our Lord. “Understand, therefore, that the Lord your God is indeed God. He is the faithful God who keeps his covenant for a thousand generations and lavishes his unfailing love on those who love him and obey his commands.” A quite mind is attained as we rest in His love, knowing that nothing can separate us from Him. A quiet mind comes from knowing “if God is for us then who can be against us?” A quiet mind comes from entering the room of trust in a loving Father and closing the door behind us. A quiet mind comes from reminding ourselves daily and throughout the day that “I have been accepted in the Beloved and the kingdom cannot be shaken.”
 John 8:36
 Deuteronomy 7:9
 Romans 8:35-39
 Romans 8:31
 Ephesians 1:6
 Hebrews 12:28