The problem here is that it is a parade...and hence mandatory.
If the Unit Church Parade was at a mosque, would that change the view of posters here? Is it okay to order Christians, Hindus, Aboriginal Peoples, Zoroastrians, atheists and agnostics to attend a an Islamic service - or even to entry an Islamic place of worship? Assuming that all the posters here would in fact be in favour of a Mosque parade, would people be okay with removing shoes on entering? Because we remove our headdress on entering a church in accordance with norms of Christianity.
Mandatory attendance, especially in uniform, at any religious service is, in my opinion, inappropriate. I'm not even sure I am okay with voluntary attendance in uniform, because despite what another poster has stated, Canada is not "a Christian Country" - it is a country with many Christians in it, and a long history of established Christianity in its communities. It has just as long a tradition of secularism, and is considered to be a secular state.
So, if it was my call, I would not hold a Church Parade for any soldiers under my command.