The Entrance Antiphon today contains one of the last promises of Jesus before the Ascension - the promise of the Holy Spirit coming upon the disciples and consequently upon the whole Church.
In granting us the power and strength we need for the mission which Jesus entrusts to us, He says: "You will be my witnesses to all the world". Matthew's Gospel formulates this mission differently: "Make disciples of all nations."
As expressed in this verse from Acts, Jesus' words constitute command and promise. He orders us to witness to the whole world and promises us that we shall indeed be such witnesses. Every command we receive from Jesus, by its very nature, is also a promise of the grace and strength necessary to obey the command, for without Jesus, without God's grace, we can do nothing.
In the Opening Prayer, we repeat Jesus' words and ask for the power of the Holy Spirit to keep us faithful and to do God's will in our daily lives. Our prayer is a cogent reminder that we cannot be witnesses to Jesus and His Gospel unless we are faithful and trustworthy companions of Jesus.
Father, send the power of Your Holy Spirit upon us, that we may be faithful witnesses to the truth of Jesus.