I've seen this argument countless times from Americans and my question to them is: When do you think this slide began? You say we came from a country similar to the US, politics wise, but I ask when? Even since its inception Canada has had the beginnings of social institutions and a multicultural state?
Since its inception Canada's goal was to unite very different people. At time, the union of Quebec with Ontairo, and the Martimes no less, seemed like a pipe dream. However it was the promise of a national railroad and removed tarrifs the eventually sealed the deal. In contrast, inception did not become as a result freedom like the US, it was due to underlying social/economic factors that were thought best resolved upon Confederation. Indeed, they were correct, it did become better.
As for secularization, Canada history has not had the same religious backbone as the United States. Canada's pre-confederation history was marred with Protestent and Catholic feuding. As a result much of the religious wording and basis was removed from law in order to unite both groups, who were predominant at the time. Civil institutions such as divorce (which didn't occur in the US till 1909), civil unions, etc were creation upon Confederation.
During the mid 40's and early 50's there was a movement that promote a greater role in the majority based, Christian influence. The government allowed Christian churches to promote education amongst First Nations. The results, as Said1 and Marbles, undoubtably were horrific. Tales of abuse persist to this day. Where this was not a reflection necessarily on Christians by any means, it did putter out the movement.
Since the 40's and 50's, things have been fairly status quo social wise. The 50's and 60's saw the rise of the Co-opertive Commenwealth Federation party headed by Rev. Tommy Douglas (who similarly was named the Greatest Canadian) which had Western, Christian social roots which would become the father of the current NDP (leftist) party. That saw the birth of Medicare, instituationalized by Lester B. Pearson, the same man who started the UN Peacekeepers.
So again I ask where sir, at what pivotal juncture in history have we strayed the path?