His father Benjamin Mathias, worked in the Wollen industry was originally of Haverfordwest, Pembrokeshire, Wales.
[1] [2] He studied at Trinity College Dublin from 1791 to 1796, where he met and was influenced by Dr. John Walker.
He a leading figure in the evangelical movement in the Church of Ireland.
He served as Chaplain to the Bethesda Chapel, Dublin from 1805 succeeding Dr. Walker, until 1835(resigning due to ill-health) and its subsidiary Schools, Asylum and Lock Penitentiary, keeping the chapel within the established church, eventually in 1825 getting officially licensed by the Church of Ireland, despite the evangelical zeal of many of its attendees and preachers who seceded.
Mathias befriended the family of the mathematician Sir William Rowan Hamilton,[5] whom he christened in 1805 in Bethesda Chapel,[6] in the parish of St.