Well I guess the mainstream party would have to be the party that gets the majority of the votes, by definition. It was Liberal for a long time, now it's Conservative and I suspect the Conservatives won't be ruling for 10 more consecutive years.
I don't feel that same-sex marriage or abortion are issues any longer. It exposes a party if they incessantly try to subjugate the rights of people, not good for attracting the swing votes IMO.
Crime is the bread and butter of this current Government. I believe the majority of legislation has been Justice bills.
I'd like to see the Government extend that program which cut wait times to more procedures.
I can't really comment on Christian politics, because I don't think religion and politics make good bed-fellows and I'm no longer a Christian.