Plenty of people think not. I don't think we are especially religious or observant.
But check out this war memorial (in Burwood). The inscription at the top says "Thanks be unto God who gave us the victory".
That tells me that we were once a religious country, given how many memorials are dotted around the country with similar sentiments. Try and raise a memorial these days with the word "God" on it and see how far you get.
Things like this are all around us, and they should remind us that our forebears were a lot more Godly than we are today. However, some people like to act like we were never a religious country, and that religion had no part to play in our history.
Well, here is a rather large fact, carved in stone and set in a prominent location - making it a bit hard to ignore. But modern revisionist historians can walk past things like this all day and never take the slightest bit of notice.
Never trust a historian who can't see what is right in front of his fucking nose.