The Isaac Errett you inquired about was named for my great-great-great-grandfather.
This branch of Erretts may have originated in Holland.When William of Orange became King of England, he supposedly tried to dilute the power of the Catholic church in Ireland by relocating Protestants there.Family legend has it that one such person relocated to Ireland was a Captain Errett serving in William's army.That's the story, anyway.
Henry Errett was born in Arklow, County Wicklow, Ireland circa 1732.His son William was born there circa 1762.William had at least two sons, Henry (b.1788) and Isaac (birthdate unknown).In the early 1800's Henry and Isaac left Ireland for North America.
Isaac settled in Ontario.Henry went to New York City, where he married in 1811, had seven children, and then died in 1825.His son Isaac was born January 2, 1820, and died December 19, 1888.Isaac was a noted clergyman and a biography of him can be found at http://www.mun.ca/rels/restmov/texts/jtbrown/coc/COC1314.HTMhttp://www.mun.ca/rels/restmov/texts/jtbrown/coc/COC1314.HTM
Russell Errett, brother of Isaac, was a three-term Congressman.
(After the death of Henry Errett in 1825, his widow remarried a man whose last name was Sutor and they moved to Sawmill Run, PA, near Pittsburgh.)