Here’s an ad from the July 16 1942 edition of the Toronto Daily Star for an upcoming church service:
The three existing Axis Powers were, of course, Germany, Italy, and Japan. “Fifth column” was a term used to describe people who undermined a group from within on behalf of an enemy.
The background for this, as far as I can tell: in September 1939, Prime Minister Mackenzie King had pledged that Canada would not introduce overseas conscription for the duration of the Second World War. By 1942, some people were advocating conscription, and a plebiscite on April 27 of that year asked voters whether they were willing to let the Canadian government release itself from its promise not to send conscripted men overseas.
83% of English Canadians supported the plebiscite, which meant that eight of the nine provinces at that time supported it. But 72.9% of voters in Quebec opposed it, which presumably aroused the ire of Dr. Shields and Rev. Martin. The conscription crisis in Canada reached a peak in 1944, and is discussed in detail in this Wikipedia page.
This blog has encountered Dr. Shields a couple of times before – most recently, here. He was the pastor of the Jarvis Street Baptist Church from 1910 to 1955. A search for Reverend H. G. Martin revealed that somebody of that name travelled to the Ivory Coast as a Protestant missionary in about 1915; I have no idea if this was the same man.
A search for “Canadian Protestant League” threatened to send me down some deep Internet rabbit holes, so I didn’t follow the results too much. I did find a reference to a book written by Reverend Shields and others in 1945 titled Why The Canadian Protestant League Was Formed. Some of the chapter titles of the book are listed in this reference, indicating that the book was anti-Catholic and anti-Quebec.