Newtown on Wikipedia.
 

All Saints (188-90). © John Balaam (2008). Grade II listed.

The former Bethel Chapel (Welsh Presbyterian, dating from 1875) on New Road. The congregation now shares the Crescent Presbyterian Church (see below). SO 110 915. © Mike Berrell.

Crescent Presbyterian Church (originally English). © John Balaam (2008).

Evangelical Church. Interior view. SO 096 907. Both © Gerard Charmley (2014).

The former Primitive Methodist Chapel. © Gerard Charmley (2014).

St. David (1843-7). © Eirian Evans. Another view. © Mike Berrell. And another, from John Bowdler. It closed in 2006, and in 2010 was up for sale. Link1. Link2. Grade II listed.

The remains of the medieval St. Mary. © John Balaam (2008). Grade II listing, which says that it fell into ruin when the congregation removed to St. David's in 1856. It was conserved in 1939.

U.R.C. on New Church Street was built as Congregational in 1876. SO 108 914. © Mike Berrell. Another view. © John Bowdler. Howard Richter has advised that this was for sale in 2016 - news item. Grade II listed.

Zion Baptist Chapel (1881). © Eirian Evans. Another view. © Mike Berrell. Grade II* listed.

There are several additional churches which Howard Richter has advised of.
A Methodist Church on Back Lane at SO 107 907, built on the site of a Wesleyan Chapel of 1835, and which was closed in 1983. Link.
God the Holy Spirit (R.C., consecrated in 1947) on Long Bridge Street at 109 919. Link.
Hope Community Church (Pentecostal, Assemblies of God) at SO 107 909. Seen here in 2009 on Google Streetview, and here in 2015, showing the church being either re-built, or extensively enlarged. Link.
Kingdom Hall of Jehovah's Witnesses at SO 110 920. A Google Streetview is available here.