The "Kingdom" in this Scripture represents those who become true followers of Jesus. "Keys" are a symbol of power to open. To the Apostle Peter was delegated the privilege and authority of first opening the message and work of the Gospel to the Jews, and later to the Gentiles. He did the opening work of the New Dispensation, first to the Jews at Pentecost, at which time as we read, "Peter stood up with the eleven"; he took the initiative, he opened the Gospel invitation to the Jews and the other Apostles followed him. There he used one key. More than three years later he used the other key to open the message of the Kingdom of heaven to the Gentiles when the Lord sent him to preach the Gospel to Cornelius who was the first Gentile to accept the Lord Jesus Christ; therefore the first to become a member of the Kingdom of heaven class. Thus we see that the Apostle Peter long ago used the keys referred to in this Scripture. There will be no occasion ever to use them again. Those who reach heaven will not pass through literal doors.