If a white dude ever told me to "go back to my country" I would stare him right in the eye and remind him that he too is an immigrant and say "that's a funny thing coming from a foreigner."
The only person I would accept a "go back to your country" statement from would be an aboriginal.
This statement and others like it display a profound ignorance and contempt of canadian society and history, which is quite disturbing considering the ever increasing amount of immigration drawing people from distant cultures into our own.
Aboriginal people did not create the country of Canada, though they contributed to it. The extent of this contribution is debatable. A country is not merely a landmass, rather it is defined through cultural, political and historical qualities. Canada is not a blank slate, it is not a post national state (yet). It is the compromise between a number of European colonial groups. There is a reason the towns in eastern ontario, just west of the ottawa river, bear distinctly scottish names, for example.
If you do a small amount of introspection on this issue, consider that it is to your benefits as new comers to overlook this preexisting culture, as this way you can avoid feeling the discomfort of contributing to its downward turn. I mention this only because it saddens me that my personal heritage seems to be fading, while those of you who are rushing to stand over it do it a dismiss it mistakenly, seeming not to know or care about it.
There is another myth which must be dispensed with. The country does not need to continue to grow its population. This argument is primarily made for political reasons and because of the greed of certain industries. Somewhat more true is that there is a demographic bubble in canada due to a generation with many children who themselves had few children nearing retirement. This issue, however, is again generally weilded for political reasons and because of greed. There is a great deal of debate over whether immigration has the ability to solve the demographic bubble, and additionally it may not as cataclysmic as is being claimed. Much of the negative prognostication is baseless, and in fact there is evidence that a sudden reduction in population (sudden in demographic terms) increases individual wealth, as the wealth of the outgoing generation concentrates in fewer hands, so they are able to put it to use making more money. This is true of farmland, as you need a certain sized plot to be productive and with larger batches of children land tends to get broken into pieces too small to be of value. However it may also be true with wealth, as you need a certain amount of wealth to be successful and not merely subsist. There is concern about the state of our massively bloated government, when and if our tax base shrinks, however this is merely empty speculation, many of use would prefer a smaller government, and it is not clear that immigration will aid or worsen the issue. Also, given the option, I would personally not trade my heritage for more government employees and public works of questionable taste.
Anyway there are some things to consider, from a different perspective than you would normally find on a forum about canadian visas.