Bishop Jacob Mar Barnabas was born on 3 December, 1960 to Geevarghese and Rachel of Aerath family at Karikulam, Ranni, Pathanamthitta in central Kerala. Lovingly called ‘Monachan’ was Baptized with the name ‘Chacko’. He was the eldest among the eight with three brothers and five sisters. Three of his sisters are nuns in the Congregation of Sisters of Imitation of Christ.
Joined the Order of the Imitation of Christ in 1975 after his schooling at Ranni and completed his Pre-Degree Course from Mar Ivanios College, Trivandrum; Took his First Profession in 1979 after his novitiate at Thapovanam Bethany Ashram, Alwaye; Did his Pre-philosophy at Papal Seminary, Pune and completed his Philosophy and Theology at Jnana Deepa Vidhyapeeth (JDV), Pune. His Final Profession was on 15 May, 1985. He was one among the first batch of theologians at Bethany Vedavijnana Peeth (BVP), Pune.
He was Ordained Priest on 2 October, 1986 by His Grace Archbishop Benedict Mar Gregorios at Mount Bethany, Mylapra. The new priest was given the charge of religious formation for pre-novices; later he was sent to Academia Alfonsiana, Rome for pursuing higher studies in Moral Theology. He presented his doctoral thesis on ‘Liturgy and Ethos’, a study based on the Malankara Liturgy of Marriage, in 1994.
During his priestly ministry, Fr. Chacko Aerath OIC held various positions of great responsibility, viz. Superior, Bethany Ashram, Pune; Rector, BVP, Pune; Professor and Head of the Department of Pastoral and Moral Theology at JDV, Pune; Visiting Professor to various seminaries including Malankara Major Seminary. He was elected as the first Provincial Superior of Bethany Navajyothi Province in 2000.
On 7 February, 2007 Pope Benedict XVI appointed him as the Apostolic Visitator with an Episcopal Character for the Malankara Community in the Extra Territorial Regions in India and the Titular Bishop of Bapara.
The Bishop designate Msgr. Aerath was ordained ‘Ramban’ on 7 March 2007 at St. Mary’s School, Ranni, Pathanamthitta and was consecrated as Bishop Jacob Mar Barnabas by His Beatitude Major Archbishop Moran Mor Baselios Cleemis Catholicos on 10 March, 2007 at St. Mary’s Cathedral, Pattom, Thiruvananthapuram. The motto of His Excellency Mar Barnabas is Vachanasya Sakshi Bhava’ (Be a witness to the word). He was enthroned in his new office at New Delhi on 22 March, 2007.