Holy Trinity Parish was established by Bishop Philbin on 1st March 1966.

Fr P. J. McKillop was appointed as the first parish priest. The parish consisted mainly of the district of Turf Lodge which had until this date been part of St Teresa's Parish. It was to be several months before the boundaries of the parish were finalised, but these matters were finally resolved by 23rd July 1966 when the name Holy Trinity was selected as the ‘titulus’ of the parish and the new primary schools which were still under construction.

For the first five years of its life the parish had no church, Mass was celebrated in St Aidan’s Primary School for several months until Holy Trinity Primary Schools were opened on 29th August 1966.

The need for a proper Church was rapidly becoming essential as the parish continued to expand, there were many pressing financial demands and to assist the parish a diocesan wide collection was authorised by the bishop and the chapter of canons on 30th June 1968.

After prolonged negotiations a site was secured for the church is Norglen Gardens which was purchased for £6,000 on 28th November 1969. Within a year work commenced on the Church, following the design of D. J. McRandal, the contractors were Baird & Ferguson based on their tender of £61,043 The Church was due to open in July 1971, but this was postponed until September this date was also postponed due to civil unrest and the halting of all building work. Eventually the opening date was arranged for Sunday 30th January 1972 although the Church was still incomplete.

The design was adapted from an industrial building which was characterised by simplicity of line and material. The exterior of the Church was constructed partly in brick and light-weight insulated cladding. It was a very large building inside, 90 x 90’ which provided seating for 1,000 people and afforded a clear unobstructed view of the altar as there were no vertical supports.

After several decades of faithful service and the enhancement of the interior the building began to show signs of wear and tear. There were persistent problems with roof and gutters, it was difficult to heat and there was little natural light except that which was filtered through fibreglass panels in the roof. After several major inspections and proposals for refurbishment it was deemed more economical to re-build . The formal announcement of this long awaited news was made by Bishop Michael Dallat when he came to celebrate the Vigil Mass for Christmas at 9pm on Thursday 24th December 1998.

Several weeks earlier on 7th December 1998 P & B Gregory Architects were appointed the architects for the New Church. Over the following months the designs were prepared and by late summer the Church was sent out to tender. The tenders were to be returned by 17th September 1999, after discussion and deliberation with the Diocesan Building Committee, O’Hanlon Brothers of Coalisland were appointed as the contractor.

On Wednesday 8th December 1999 at 7.3Opm Fr Matt Wallace assisted by Fr Thomas McGlynn celebrated the final Mass in the Old Church. Demolition began on 16th December 1999 and was completed by January 19th 2000.