I searched the Irish Family History Foundation's database. It contains 11,500,000 surviving rcds for abt 60% of Irish counties. Co Antrim rcds are in the database.
For James O'Neil (+variants) B 1847 +/- 4 yrs, I found 68 matches in Antrim. For Sarah Dynes in the same range, I found 1 match in Co. Armagh in 1845.
For a marriage of the two in 1850 +/- 4 yrs, I found 1 match for Sarah Dynes in Co. Armagh in 1854. For James O'Neil, I found 11 matches, but none in 1854. Without corresponding matches in the same yr in the same county, these are NOT your ancestors.