A self-educated immigrant from England, Shields was the longtime pastor of the Jarvis Street Baptist Church in Toronto.
Early in his ministry Shields proudly related that, as his pastor and theological professor, his father taught him "nearly all I have learned."
He had pastorates also in Dutton (Elgin) 1895, Delhi (Norfolk) 1897, and Hamilton (Wentworth Street Baptist Church) beginning in November, 1900.
In a bit of irony, Shields (not knowing the full picture) was used by the Convention in 1910 to put forth a motion to quell the inquiry surrounding the professorship of Isaac George Matthews at McMaster University that Elmore Harris had begun.
In 1919, when an anonymous editorial in the Canadian Baptist attacked the doctrine of Biblical inerrancy, Shields presented a strong condemnatory resolution to the annual convention.
Shields and others were highly concerned that McMaster had conferred an honorary doctorate upon William H. P. Faunce (president of Brown University).
At one point a radio station was purchased and given the call letters CJBC (Jarvis Street Baptist Church.)