I dont understand this criticism. We live in a democracy and our laws reflect the will of the majority. If the majority want Christian-friendly laws, then gr8. But the Church doesnt insist on this and we make no effort to govern. Certainly we make our case forcefully in society, but much of the 'Christian law' you complain about, in this country anyway, is based on sound natural law about the dignity of life, the value of personal property, the right to equality before the law etc. Most people would not bother to argue with the whole swag of what Christians approve of in a legal-political sense; they are truths which are virtually self-evident.
We acknowledge Christ as both head of the Church and all government, but these two can only be united in the next world. The Church cannot govern and it must not govern. Your issue is with the Australian people, not us.