Wouldn't work in Australia - that'd mark you out immediately as a real suck. Better something along the lines of -
"Love Lives Here
would be a more appropriate sign and in the true spirit of Australia.
Any mention of religion would suggest to your neighbours that you consider yourself somehow holier than them, which is unwise especially if you need to borrow something. So if you are inclined to talk to the god botherers best keep it to yourself. In any case finding a functioning church in Australia if one has the strange desire to want to find one is getting more difficult as religious attendance has thankfully collapsed - been that way for years. As for the flag and constitution, they exist but we don't get all misty eyed about them - there's better things to get misty eyed about like beer.