Rev. Colin Mercer was converted to Christ at the age of eight. He commenced attending his local Free Presbyterian Church in Londonderry, Northern Ireland, as a young teenager and soon became involved in the ministry of that congregation. He served as a Sunday School teacher and participate in Youth meetings and open air services. In 1988 he was called by God to prepare for the gospel ministry and consequently in September 1989 commenced studies in the Theological hall of the Free Presbyterian Church of Ulster. On the completion of his studies he accepted a call from the Castlederg congregation and was ordained and installed on 21st January 1994. In 1999 Rev. Mercer moved to Mourne Free Presbyterian Church. The work in Mourne includes a Christian day school which caters for both primary and secondary education. In 2009, Rev. Mercer replaced Alan Cairns as the senior minister of Faith Free Presbyterian Church in Greenville, SC.