Peter continues to preach and announces,
Let all the house of Israel therefore know assuredly that God has made him both Lord and Christ
We are so accustomed to the titles that we have a hard time even imagining how they sounded to the original audience. In the Greek translation of the Old Testament which we called the Septuagent, wherever the name of God appear יהיה the translators used the word Kyrios, Lord. We have continued the tradition in the Catholic Bibles today. The other use of the word Kyrios was in reference to the King. Caesar would have been called in Greek Kyrios.
When Peter proclaims Jesus as Lord and Christ, he is making a radical announcement. Jesus is not only the fulfillment of the prophecies regarding the sending of a Messiah to set the people of Israel free; he is the Kyrios, in every sense of the word.
Through baptism he tells them that their sins are forgiven, they receive the Holy Spirit, and they become part of the Kingdom of the one and only true Kyrios.
There are some Greek words that every Chrisitan should know. To this day the one remaining part of mass in Greek is the Penitenial Rite Kyrie ( a form of Kyrios) eleison. Whenever we hear or say the word Lord in our prayer we should recall all of the layers of meaning attached to that word. For the first hearers to say that he was Lord and Christ would have implied that there was only one appropriate response, absolute loyalty and complete submission.
On this third day of Easter as we hear of the Baptism of 3000 and the birth of the Church perhaps it is time for us to unite our hearts with theirs and renew our true belief that Jesus is our Lord and Christ.