Charities must have exclusively charitable purposes.  They cannot have political purposes.  Purposes are the legal objects of the charity.

Here is an excerpt from CRA Guidance on Political Activities – CPS-022

“4. The difference between political purposes and charitable purposes
All registered charities are required by law to have exclusively charitable purposes. As the Act does not define what is charitable, we look to the common law for both a definition of charity in its legal sense as well as the principles to guide us in applying that definition.[Footnote 2 -Vancouver Society of Immigrant and Visible Minority Women v. M.N.R., [1999] 1 S.C.R. 10, at para. 143, Iacobucci J.] The formal objectives or goals of a charity must be set out in its governing documents.

Under the Act and common law, an organization established for a political purpose cannot be a charity. The courts have determined political purposes to be those that seek to:
• further the interests of a particular political party; or support a political party or candidate for public office; or
• retain, oppose, or change the law, policy, or decision of any level of government in Canada or a foreign country.

The main reason why the courts rule out political purposes for charities is a result of the requirement that a purpose is only charitable if it generates a public benefit. A political purpose, such as seeking a ban on deer hunting, requires a charity to enter into a debate about whether such a ban is good, rather than providing or working towards an accepted public benefit.

It also means that in order to assess the public benefit of a political purpose, a court would have to take sides in a political debate. In Canada, political issues are for Parliament to decide, and the courts are reluctant to encroach on this sovereign authority (other than when a constitutional issue arises).[Footnote 3 -McGovern v. Attorney General (1980) [1981] 3 All ER 493 at 506e (C.A.).
]
It is important to remember that although the stated purposes of an organization are the obvious source of reference of whether or not an organization is constituted exclusively for charitable purposes, it is not the sole indicator. The Canada Revenue Agency also takes into account the activities that the organization is currently engaged in as a potential indicator of whether it has since adopted other purposes.[Footnote 4 -Vancouver Society of Immigrant and Visible Minority Women v. M.N.R., [1999] 1 S.C.R. 10 at para. 194, Iacobucci J.]”

Here is a link to CRA Guidance on Political Activities – CPS-022 http://www.cra-arc.gc.ca/chrts-gvng/chrts/plcy/cps/cps-022-eng.html

As well here is a copy in PDF of the CRA Policy Statement on Political Activities by Canadian Charities CPS-022 – September 2, 2003 so that you can download it easily to your computer.