Puritan Board Junior
A Reformed church has to hold to one of the Confessions though. correct?
And someone like a John Macarthur would be calvinist, but not reformed?
1- Correct. Many would also argue for an even stricter definition that would not include Baptists. While I am one of those, it is for sake of clarity of terms and not to speak less of my brothers of a different ecclesiology.
2- JM is a strange bird: I would call him Calvinistically-leaning Dispensational Baptist.