Thomas Mor Alexandrios, previously known as Thomas Abraham Neriyanthara, is a prominent figure in the Malankara Jacobite Syriac Orthodox Church. Born in 1971 in Panampady, Kottayam, Kerala to Fr. N. M. Abraham and Mrs. Elizabeth Abraham, he was baptized at St. Mary's Jacobite Syrian Orthodox Church Panampady, Kottayam, his home parish.

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After completing his graduation, Thomas Mor Alexandrios pursued theological studies at the Presbyterian Theological Seminary in Dehradun, where he obtained his Bachelor of Theology (B.Th.) degree. He furthered his education at Beracah Bible College & Seminary, Thiruvallur, where he earned a Master of Divinity degree. He also holds a diploma in Philosophy from Mor Aphrem Seminary, Vadavathoor, Kottayam, Kerala.

Thomas Mor Alexandrios was ordained as a deacon on 15 March 1997, by Joseph Mor Gregorios, and later ordained as a priest on 15 May 2004, by Thomas Mor Themotheos. He served as vicar in St. Peter's J.S.O Church, Chicago, USA, and St. Mary's JSO Church, Vellore, Tamil Nadu. In 2012, he was appointed Metropolitan (Bishop) with the name Thomas Mor Alexandrios at the Puthencuriz St. Athanasious Cathedral by H.B Baselios Thomas I.

Thomas Mor Alexandrios is also the founder and director of Santhwana Guidance & Counselling Centre in Vellore, Tamil Nadu, which was consecrated by Baselios Thomas I on 24 March 2012. He was later appointed as the Metropolitan of Mumbai diocese by the synod of the Jacobite Church on 13 June 2013. In 2023, he was further honored by the Patriarch of Antioch, Moran Mor Ignatius Aphrem II, who appointed him as the Patriarchal Vicar of Ireland.