County Down on Wikipedia.

Annahilt, Church of the Ascension, (Church of Ireland). © Jack Storey, Monaghan Genealogy Specialist.
Ardglass, Church of Ireland. © 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).
Ballyroney, the Presbyterian Church. © Jack Storey, Monaghan Genealogy Specialist.
Banbridge.
Bangor.
Bleary, Gospel Hall. J 077 538. © Gerard Close.

Carrowdore, Christ Church (CoI). Many members of the Crommellin family of Carrowdore Castle are buried here. © Jack Storey, Monaghan Genealogy Specialist.
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).
Crossgar, Christ Church (Church of Ireland) at Kilmore. © Jack Storey, Monaghan Genealogy Specialist.

Donaghcloney, Methodist Church. © Jack Storey, Monaghan Genealogy Specialist. Presbyterian Church, from an old postcard in Reg Dosell's Collection.
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).

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, Methodist Church. J 146 604. © Gerard Close.

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).
Newry.
Newtownards.

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.

Tullylish, All Saints (CoI). J 081 486. © Gerard Close (2011).

Waringstown, the Donacloney Parish Church (CoI). J 103 552. Presbyterian Church (1853). J 105 553. Both © Gerard Close.
Warrenpoint, St. Peter (R.C., 1840). J 141 182. Methodist Church. J 141 182. Both © Gerard Close (2011).