In the year 2006, The Holy Episcopal Synod, with the permission of Supreme Head of the Church, Ignatius Zakka I Iwas, decided to split Ankamali Diocese—the largest Diocese in the Universal Syrian Orthodox Church—into four regions, which was later approved by the diocesan council. A special meeting of vicars and representitive of churches of Highrange region was held and elected Fr. James Chitteth as metropoitan unanimously of that region .The nomination of The Highrange region was approved by the Council of Anakamy diocese. subsequently The election was approved by the Managing Committee, Working Committee, Malankara Episcopal Synod and later by Ignatius Zakka I Iwas.
At Karingachira St. George Jacobite Syrian Cathedral, Baselios Thomas I ordained him as Rabban (monk) with the name Nahum on July 2, 2006, along with four others.On July 3, 2006, Nahum Rabban along with four other monks, was raised to the highest order of bishophood—metropolitan—by Baselios Thomas I, at St. Thomas Jacobite Syrian Orthodox Church, North Paravoor, where Patriarch of Antioch, Moran Mor Ignatius Peter IV consecrated St. Gregorios Geevarghese, Chathuruthil along with others in 1876. Rabban Nahum was ordained with the name MOR APHREM MATHEWS. He is the only Metropolitan in the Universal Syrian Orthodox Church with the name Aphrem. Mor Aphrem was given charge of High Range Region of Ankamali Diocese, under Baselios Thomas I, who is the diocesan Metropolitan.His Sunthronizo was done at St.George Syrian cathedral Adimaly and his Salmoosa was read there.
Metropolitans Thanono Dr.Yuhanon Mor Philaxinos, Dr.Thomas Mor Timotheos, Dr.Joseph Mor Gregorios, Dr. Mor Ivanios Mathews, Yuhanon Mor Militos, Mor Yulius Kuriakose, Mor Dionysius Geevarghese, Dr. Mor Theophilos Kuriakose and Mor Severios Kuriakose assisted Catholicose in the consecration.
During his ministry he took intitaitive in constructing the new centre in Adimaly called Mount sehion. He is also instrumental in building new Chappel in the centre.He took special interest in conducting bible convention at regional levels in highrange area that helped spiritual renewal of that area.
Later he was transfered from Highrange region to Perumbavoor region of the Ankamaly diocese. Now his headquarter is at Koinonia at Allapra. Apart from these diocese he also served as the Patrirchal vicar of UAE and UK for the term of three years.During his ministry in UAE, he completed the construction of Al Ain St. George church and St. Gregorios church Ra Al khaima and St. Peters Church Fujarah. while he was in UK as patririarchal vicar he started new congregations there and organized churches there. He took special interest in arranging students camp in Uk and taught faith and practice of the church to the children.
