As a Christian, I can agree that theists would feel that “God keep our land” would not express their feelings about Canada.
Sadly, history has shown that leaving out God and simply depending on human nature and responsibility has not worked well. Since 1789, godless regimes showing brutality, injustice and lack of compassion have built walls to keep people from escaping.
Related: Canadian anthem discriminates
While many nations give lip service to being Christian, it would be wonderful to see a land really following God-given principles found in the scriptures. David Lethbridge might even find it a good place to live.