This New Testament letter is a circular catechetical piece, the very crown of Pauline theology, and written by the Great Apostle while he was an "ambassador in chains" in prison. This sacred text unveils God's mystery and the unsurpassable riches that all believes possess in Christ. It is of massive pedagogic import for the Christian life, revealing both the saving acts of the Holy Trinity on our behalf and the contours of a Christian walk that is worthy of the Gospel.