First, the context of this complaint was in an article about conservative Christian activists getting party nominations for the Conservative Party. Is this what amounts being kept from the public square these days?
Second, there are "people of faith" in every party in the parliament already. My understanding is that there are even devout Christians in every party in the House. Not only are believers of all stripes not being kept from the public square, they are already in there.
So what's the complaint about now? Well, I reckon it's more of a straw man. Whenever you get conservative Christians saying stuff about faith being kept out of the public square, it's usually as a rebuttal to accusations about "hidden agendas" and stuff of that sort. The question of a hidden agenda is quite apart from the question of whether people of faith are in the public square. The fact is that the Conservatives are trying to appeal to a broad range of voters. At the same time, their social-conservative base has some things that it would like to accomplish. Most strategists and pundits will tell you that it is possible to build a winning coalition in Canada by being fiscally conservative but socially ambiguous. On some level the Liberals have done this with a very subtle socially progressive bent. That's not what the so-cons want though. There is nothing wrong with that either, everyone is entitled to their ideas and the promotion thereof. The problem is that I imagine Stephen Harper wants to have his cake and eat it too. He wants the vigourous support of the so-cons, but he wants to avoid having to acknowledging their agenda in public. So by all means, no one is trying to dissuade anyone from seeking office, but it's time to own up the agenda that that run is driven by.
And another thing: Why is the "Christian" agenda always only two items long. It's all about gays and abortion, it's as if nothing else is of concern. What about the poor? What about the sick? As Jim Wallis would remind us, Jesus worried about them.