"She had imbibed her ideas from the doctrines of one flaming predestinarian divine alone"

The flaming predestinarian in question is John Calvin. His teachings had a huge influence on the austerity so resented by the laird (and, implicitly, the Editor), but it was perhaps his doctrine of predestination that provoked the most controversy. Calvinism states that God, who has ordained all events in advance, has sovereign control over the ultimate destinies of his creations. Furthermore, as a result of the fallen condition of mankind, nobody is capable of true righteousness and salvation occurs as a result of God’s grace alone. Thus each woman and man is consigned from the start to either divine election or to damnation; their faith and virtue, or lack of, is immaterial.