(3) Christians Can Handle Other Worldviews

Christians can handle social cohesion better than any other worldview - but like Frodo. 
In Tolkien's Lord of the Rings, whoever carried that Ring was corrupted by its power. Even a pure heart like Frodo's. Likewise, whichever worldview carries the responsibility of being the reference point for government can be corrupted by its power.

Yet, despite the hazards, Christianity remains the worldview best equipped to handle state power in the presence of other worldviews. That includes best equipped to handle proper separation of church and state. 
Why so?

1. Christians seek to protect their freedom to maintain their worldview, along with others.
This is reasonable, as any other worldview would do. They have learned from history what it is like to have that freedom taken away, and sought to make societies that do protect it.  

2. Christians seek to protect the freedom of others to maintain their worldviews.
Even though Christians may persuade in hopes that others might join their worldview, they know that they must allow others the freedom to believe differently. This was always present (Jos24:15. Mat 19:22. 23:37.), but painfully forged into a firm conviction during the Reformation. It became a feature of the Judaeo-Christian-founded state projects of America and Australia.
Being a religion/worldview, Christians recognise how important worldviews are to people, in all areas of life, including shared political life. Christian leadership is service, so we make room for others, for freedom in moral values matters. Politics can adversely impact that freedom, even more so if it ignores moral worldviews/religions.
By contrast, Socialism (in my previous post) seeks the removal of religious worldviews from shared public discourse. Sharia can tax, limit, and threaten non-believers, with both political and military features in its worldview. And should indigenous groups regain sovereignty, what impact will come from tribal disputes?

3. Christians have forgiveness built in.
Forgiveness is the only way forward for some otherwise intractable social justice conflicts. This is integral to Christianity more than any other worldview. 

4. Christians don’t ultimately want political power.
Rather, they look forward to a day when their King returns, and the poison ring of political power will be thrown into the fire. When he comes, that King will then sort out believers and non. Until then, wheat and weeds grow together. (Mt13:30).
Contrastingly, Islam seeks global Sharia, with political and military features, and infidels would pay tax or death. Socialism wants State power for itself; it is their worldview. Indigenous worldviews claim to want their sovereignty back - we don’t know at what cost. 

5. Christians believe that God raises governments for his purposes.
(Rom 13:1,2) The more people reject God, the more the government they get will become what they deserve. This is both a judgement and a corrective to return to the Creator and His life-giving ways. The more people follow God, the more productive the government will generally be. 

6. Christianity seeks both diversity and unity.
Diversity is good, as seen in creation, and the many tribes and nations God aims to draw together (Rev 7:9. Gal3:28). Christianity is not bound to one culture - it is the most multicultural religion in the world. So Christian governments are more likely to celebrate cultural diversity. 
But in a unifying way. Not diversity that becomes splintered idols of self-centredness from which pecking order and conflict ensue. Rather, Christians celebrate diversity within the limits of God’s created order, rather than our fallenness. 
This diversity does also allow nonbelievers to diverge outside the created order, as seen in #4. Why? Because even despite our diversity for good or ill, Christians see humanity as united by a primary identity - that we are all God’s children, even unbelievers (Acts 17:28). When Christians look at anyone, that’s what they see. This unity in diversity is good for governance - it respects us all, even when restraint is needed. 

7. Christianity as a government reference point has a good track record.
Looking at its history in Rome, Europe, America, Australia and the Pacific Islands, Christianity has had a generally good impact on governments and societies, particularly in the area of religious freedom and social cohesion. Why? For the reasons listed above. 
Its record is not unblemished by any means. But any failings were not features of Christianity, but bugs caused by people’s fallen departure from Biblical belief and practice. Thus by both their use and misuse, Biblical values are proven to work in practice. They'd only work so consistently if they were true. Thus, we have a large body of consequential evidence for the veracity of Biblical truth claims. 
Consider the alternatives. What if other worldviews had come to govern those geographies? Islam historically takes over by ballot or bullet, and enforces itself to the exclusion of others. Socialism's record is similar. Indigenous worldviews have tribalism and conflict built in. These are features of these worldviews, not bugs. 

A Christian reference point for government works like Community Organising, which developed from the Christian roots of unions. In this model, people of goodwill from any worldview come together to cooperate on matters of common concern - even though their worldviews’ motivations may differ. 

Why do we need the Bible as a reference point for government? Because without a commonly agreed reference point, the union will split and tribal-ise into power plays. Our federal founders knew, based on reasons such as those listed above, that Christianity is the worldview with the most potential to unite the Federation. That's why the first sentence of our Constitution's Preamble contains the words, "humbly relying on the blessing of Almighty God." 
 
Only Christianity can bear that Ring of political power safely to its end.