Hugh & Mary’s marriage is normally available to view free on the irishgenealogy site. However that site is down at the moment (and has been for the past 4 or 5 days). In the meantime, you can pay to view the certificate on the GRONI website for £2.50 if you wish.
From the trees on Ancestry Hugh & Mary both came from Procklis. That’s a townland on the modern Whiteside’s Rd about 4 miles north of Randalstown. Hugh’s father was George, a labourer. Mary’s father was John, a yarn manufacturer. (Co. Antrim was a big weaving area). Witnesses were Samuel Campbell & Mary Lindsay.
I can’t answer your question about where the Lindsay & Campbell families came from but both surnames are fairly obviously Scottish and most of the population in that area are descended from Scots who arrived in Ireland in the 1600s. So I would guess they were born in Ireland but of Scots descent, in the 1600s. Today we call them Ulster-Scots. (Generally don’t see themselves as Irish and are very keen to retain their links with the rest of the UK).
Here’s Wikipedia’s take on Plymouth Brethren:
https://en.wikipedia.org/wiki/Plymouth_BrethrenNote that by 1911 your family had switched from Brethren to Church of Ireland (ie Episcopalian). Prior to the mid 1800s I suspect they were likely Presbyterian (the main Scottish denomination).
