"Peace on earth" was first proclaimed by the angels when they announced to the shepherds the birth of the Savior, Jesus Christ. It is only by the mercy of God through His Only-Begotten Son Jesus Christ our Lord, that the world became exposed to real 'peace.' Heaven and earth could finally be reconciled. In the Divine Liturgy, we pray the short and sweet hymn, "Through the intercession of the Theotokos Saint Mary...." after the Prayer of Reconciliation and greeting one another with a holy kiss. The hymn begins with recognizing the role of the Virgin Mother who accepted her call in God's plan of Salvation. Therefore, it is on her heels, that we were granted to become children of God and can now worship Him and ask for His forgiveness through His mercy.
The apostle Paul teaches us in his letter to the Hebrews 13:15 why and how to offer a 'sacrifice of praise': "Therefore by Him let us continually offer the sacrifice of praise to God, that is, the fruit of our lips, giving thanks to His name." There was once a set of obligations and rules that were established to help govern God's people and to keep them holy by offering sacrifices for specific reasons. These sacrifices became extinct once the Savior came and gave us Salvation, for He is the Lamb of God who takes away all of our sins.
David the prophet also mentions what God is alluring us to in regards to an acceptable sacrifice from us: "The sacrifices of God are a broken spirit, A broken and a contrite heart—These, O God, You will not despise" (Psalm 51 NKJV). Christ is the only acceptable Sacrifice and there can be no other sacrifice that would suffice. Thus, all we can offer is a contrite and repentant heart and praise.
