County Down on Wikipedia.

Annahilt, Church of the Ascension, (Church of Ireland). © Jack Storey, Monaghan Genealogy Specialist.
Ardglass, St. Nicholas (CoI). J 558 371. © Jack Storey, Monaghan Genealogy Specialist.

Ballygilbert, Presbyterian Church (1842). J. 453 807. © Gerard Close (2011).
Ballygowan, Presbyterian Church. © Jack Storey, Monaghan Genealogy Specialist.
Ballykinlar, St. Patrick and St. Joseph (R.C.) at North Tyrella. © Len Brankin.
Ballymartin, St. Joseph (R.C.). J 342 167. © Gerard Close (2011).
Ballynahinch, St. Patrick (R.C., 1812). J 366 522. Methodist Church. J 362 527. Both © Gerard Close (2016).
Ballyroney, the Presbyterian Church. © Jack Storey, Monaghan Genealogy Specialist.
Banbridge.
Bangor.
Bleary, Gospel Hall. J 077 538. © Gerard Close.

Carnalea, St. Gall (CoI). J 475 816. © Gerard Close (2014).
Carr, Baptist Church. J 335 629. © Gerard Close (2013).
Carrowdore, Christ Church (CoI). Many members of the Crommellin family of Carrowdore Castle are buried here. © Jack Storey, Monaghan Genealogy Specialist.
Carryduff, Baptist Church. J 363 649. © Gerard Close (2012).
Cloghogue, Church of the Sacred Heart (R.C., 1916). J 082 237. © Gerard Close (2012).
Clough, Church of Ireland. © Jack Storey, Monaghan Genealogy Specialist.
Comber, 1st Comber Presbyterian Church. Comber 2nd Presbyterian Church. Both © Jack Storey, Monaghan Genealogy Specialist. Alla Church. From an old postcard in Reg Dosell's Collection. Methodist Church. J 460 694. © Gerard Close (2011). St. Mary (CoI) was founded as a Cistercian Abbey in 1199. J 459 692. © Gerard Close (2012).
Conlig, Presbyterian Church (1848). J 499 782. © Gerard Close (2011).
Craigavad, Gospel Hall (1956). J 442 809. © Gerard Close (2014).
Crossgar, Christ Church (Church of Ireland) at Kilmore. © Jack Storey, Monaghan Genealogy Specialist.

Donaghadee, the Parish Church (CoI, 1888). J 588 798. Link. Free Presbyterian (1991). J 589 798. Link. Shore Street Presbyterian (1821). Link. All © Gerard Close (2018).
Donaghcloney (or Donacloney), St. Patrick (CoI). J 129 536. © Gerard Close (2014). Methodist Church. © Jack Storey, Monaghan Genealogy Specialist. Presbyterian Church, from an old postcard in Reg Dosell's Collection. Elim Church. J 129 538. © Gerard Close (2014).
Downpatrick.
Dromore.
Drumballyroney, Church of Ireland. Famous for its Bronte connections, several members of the family are buried here, and Charlotte and Emily's father preached here. © Jack Storey, Monaghan Genealogy Specialist.
Drumbeg, Church of Ireland. © Jack Storey, Monaghan Genealogy Specialist. An old postcard view, from Reg Dosell's Collection.
Drumbo, Ballylesson Trinity Church, (Church of Ireland). © Jack Storey, Monaghan Genealogy Specialist.
Dundrum, Sacred Heart (R.C.). © Len Brankin.

Gifford, St. Paul (CoI). J 062 488. Presbyterian Church (1845). J 064 485. Free Presbyterian Church. The date stone says 1848, but as Gerry advises, this cannot refer to an originally Free Presbyterian Church, as this was only founded in 1951, so what was it built as? All © Gerard Close.
Glencraig, Holy Trinity (CoI). J 437 813. © Gerard Close (2011).
Granshaw, Presbyterian Church, on Gransha Road. J 412 690. © Gerard Close (2020). Link.

Helens Bay, St. John the Baptist (CoI). J 454 828. Presbyterian Church. J 458 822. Both © Gerard Close (2014).
Hillsborough.
Holywood.

Katesbridge, Presbyterian Church. © Jack Storey, Monaghan Genealogy Specialist.
Killinchy, Parish Church. © Jack Storey, Monaghan Genealogy Specialist.
Killyleagh, Presbyterian Church. Church of Ireland. First Killyleagh Presbyterian Church. All © Jack Storey, Monaghan Genealogy Specialist.

Lambeg, Church of Ireland. © Jack Storey, Monaghan Genealogy Specialist.
Lisburn. Lisburn straddles the border of Counties Down and Antrim - the county boundary being the River Lagan (see Wikipedia entry).
Listooder, the Kilmore Presbyterian Church. © Jack Storey, Monaghan Genealogy Specialist.

Magheralin, Church of the Holy & Undivided Trinity (Church of Ireland). © Jack Storey, Monaghan Genealogy Specialist. St. Patrick (R.C.). © Len Brankin. Link. The Evangelist Memorial Hall. J 125 589. © Gerard Close.
Moira.

Newcastle, the former St. Mary (R.C.), now a community centre. J 376 312. Methodist Church. J 374 305. Both © Gerard Close (2011). Presbyterian Church. J 375 315. © Gerard Close (2012). St. John (CoI). J 374 299. © Gerard Close (2012). Church of Our Lady of the Assumption (R.C.). J 377 314. © Gerard Close (2012).
Newry.
Newtownards.

Priesthill, Zion Methodist Church on Kesh Road. J 222 605. © Gerard Close (2020). Link.

Rademon, Non-Subscribing Presbyterian Church. © Jack Storey, Monaghan Genealogy Specialist.
Raffrey, Presbyterian Church. © Jack Storey, Monaghan Genealogy Specialist.

Saintfield, Church of Ireland. © Jack Storey, Monaghan Genealogy Specialist.
Saul, St. Patrick's Memorial Church (CoI). This sign tells its story. Both © Jack Storey, Monaghan Genealogy Specialist. Two interior views - 1, 2, both © Adam McCurdy (2015). A distant view of St. Patrick (R.C.). © Adam McCurdy (2015).

Teconnaught, Church of the Holy Family (R.C., 1899). J 433 491. © Gerard Close (2016).
Tullylish, All Saints (CoI). J 081 486. © Gerard Close (2011).

Waringstown, Holy Trinity (CoI). J 103 552. Presbyterian Church (1853). J 105 553. Both © Gerard Close. Annaghanoon Christian Ministries Meeting House. J 115 527. © Gerard Close (2014).
Warrenpoint, St. Peter (R.C., 1840). J 141 182. Methodist Church. J 141 182. Both © Gerard Close (2011). Parish Church (CoI, 1826). J 141 182. © Gerard Close (2012).