I research the Irish Family History Foundation's database. It contains 12,700,000 surviving rcds for abt 72% of Irish counties. Rcds are increasingly sparse B4 1840, rare B4 1800. Co Donegal rcds were added to this database July 7, 2009.
Note 1 - Without a KNOWN county, the chance of an ancestor's rcds NOT being in this database is AT LEAST 35%.
Note 2 - Only 1/2 of Co. Cork's rcds are in this database.
Note 3 - The RC church kept control over most parish rcds from Tipperary (north). These are ONLY available thru the Tipperary Family History Research center at a substantial fee (regardless of outcome).
For Robert Dickson M 1858 +/- 4 yrs, Co. Antrim, I found 4 rcds: 1854, 1855, 1857, and 1861.
For Eliza Holland M ditto, I found 1 rcd in 1854. This is a POTENTIAL match to the 1854 rcd for Robert. Suggest you visit this database and screen these at the parish level to see if there is an exact match there. If so, the rcds are highly likely to be for these ancestors. A view of the detailed rcds should show whether the marriage was to each other. If so, the rcds SHOULD show their parents' names as well as other details.
From the sound of the surnames, their ancestors were likely Scots-Irish, or English transplants. This infers they were protestant. Protestant rcds weren't the best for details.
Google the Foundation's name to lead you to this database. Register, opt to be notified as rcds are added and browse. Pls post your search results to my genforum msg.