“The mark of oneness reflects the unity of the Trinity. The Holy Spirit, the bond of love between the Father and the Son, unites all the members of the Church as the one People of God. The Church professes one Lord, one faith, and one Baptism and forms one body (cf. CCC, no. 866) under the leadership of the Holy Father, successor to Peter the Apostle. Within the Church there is a diversity of races, nations, cultures, languages, and traditions, which are held together in one communion by the gift of love from the Holy Spirit. The unity that Christ bestowed on his Church is something she can never lose (cf. Second Vatican Council, Decree on Ecumenism [Unitatis Redintegratio; UR], no. 4; CCC, nos. 813, 815). Today, we experience that unity among Christians in martyrdom and worldwide persecution of our fellow Christians. Watch this documentary on the challenge of persecution, martyrdom and Christian ecumenism in "Under Caesar's Sword."Download the Study Guide by clicking here!