I believe he joined the LDS Church as a young adult, so no, he was not born a Mormon.
Harry Reid was born on December 2, 1939.
Harry Reid - publisher - was born in 1947.
Harry Fielding Reid was born on 1859-05-18.
Harry Reid was born on December 2, 1939.
Harry Reid was born on December 2, 1939.
Darrel Reid was born in 1957.
Miles Reid was born on January 30, 1948.
Christopher Reid was born in 1949.
Curtis Reid was born in 1836.
Eoin Reid was born in 1985.
Reid Walker was born in 2000.
Jimmy Reid was born in 1932.