When a country like Canada enshrines "freedom of conscience and religion" in its Charter of Rights and Freedoms, it gives itself a particular challenge. When that country seems determined to support multiculturalism, that challenge takes on further dimensions.
As a Secular Humanist, I am biased toward the precedence of state law, if that state is secular. That said, I am also committed to the ideal that freedom of religion is just as necessary a part of our democracy as freedom from religion.
State laws in a democracy should reflect the will of the people and are enacted to provide a stable society that is just and peaceful ("peace, order, and good government"). To work, the state must apply them justly and equally to all people without exceptions because of personal philosophy or belief.
Easier said than done.
Church laws apply only to those people who choose to accept them and the state must resist attempts by religion to apply them to people outside that religion. Many religious laws, such as Kosher and Halal laws, don't affect the general public; others do brush against the Charter of Rights and Freedoms and these are the laws of concern.
However, even in these cases, unless the individual who is offended by the church law speaks out, how can the state intervene? If a religion has rules (religiously justifiable or not) that say, for example, women are not equal to men, or if a religion defines women's equality in a way that does not meet Charter standards, should the state intervene?
Since any individual who feels that Charter rights have been violated can take the religion in question to a Human Rights Tribunal, the state must participate in such cases. Of course, the individual will likely be intimidated by the religion and its leaders against taking such action and would probably have to leave the religion or at least the sect upon making the challenge. Family pressures would also be intense. Just ask any first generation atheist.
If that intimidation violates the law, and it often does, then the state has an obligation to pursue those charges if it becomes aware of them.
The case of child marriages is particularly troublesome, not only because it occurs, but also because the state has a difficult time enforcing the minimum age of 16 for marriages. Religions that insist on marrying children younger than that often see their marriage ceremony as the only legitimate marriage and disregard the civil marriage laws at least until the children become of legal marrying age.
In this case only moral suasion and education can make younger members of religions realize that there are alternatives, and that approach can only be effective it the state is prepared to shelter those individuals who choose to leave the religion and their community.
The only answer, then, seems to be that the state should challenge religion if it tries to impose its laws on the rest of the population, as it did for years with the Lord's Day Act, or as it still does in Ontario's Education Act (Section 264(1)c), which requires teachers to "to inculcate by precept and example respect for religion and the principles of Judaeo-Christian morality." Otherwise, the state is relatively powerless -- as it should be if we are to respect the separation of church and state.
A remaining problem is that immigrants to Canada often come here under the impression that freedom of religion is limitless and expect that any rules or laws made by their religion are exempt from the Charter and from the moral framework of the country. Often this is solved in only generations by the exposure of younger people to Canadian society when they realize that they have more rights than their elders suggest.
Perhaps a solution to, or at least a way to manage, that problem can be achieved by ensuring that immigrants (and everyone else) understand the Charter of Rights and Freedoms, including the limits implied by the guarantee of personal freedoms therein.
The Canadian state, then, can and should interfere with religious law if a religion attempts to impose its laws on society in general, or if an individual brings that religion before Canada's tribunals and courts for remedy under the Charter of Rights and Freedom.