One of the first things learned in the Freedom Academy is the vital importance of reason. Understanding liberty must begin with rational examination, not mythical belief. This is fundamental, and a society free of government will not, as I see it, come about while the prevailing mind-set stays mired in superstition.
Religions fit that mind-set. I know, for I was deep into one myself and am amazed now at how poorly I once examined my premises. I supposed there exists a god, but failed to check either the evidence for that amazing idea, or even what the term meant! How can anyone believe in something without even defining what it is?
There's not much dispute about this. Christians revel in the assertion that they live by faith and not by reason. There have been attempts to fuse the two - notably by Thomas Aquinas - but ultimately they know that god cannot be proven to exist. So they live by faith.
That religion sprang from Judaism, of which I think the same is true. The holy book for each begins with "In the beginning, God created the heavens and the earth." Notice that it does not say there (or anywhere else) something like "For the reasons detailed in Appendix One, we conclude that the heavens and the earth had a beginning, and that a supernatural being caused them to exist." Little wonder: someone might read it and ask "Okay, but who created that being, and what does 'supernatural' mean?" Oops.
Islam claims, I hear, also to derive from that "Book", but is a separate religion only because Jewish elders sensed that Mohammed was not a genuine prophet, and turned down his application. So he returned to Mecca in a huff, and crafted his own and spread it by force, being a warrior as well as a mystic. Religion, State and War were never more closely fused than in his person.
And so, fast-forward to the present day.
The State of Israel exists because Jews fervently believe that their god gave them a plot of land East of the Med, and because they lobbied effectively in London and Washington for support in setting it up and preserving it ever since. Religion is therefore at the heart of that state, and the cause of most of the current warfare in that region.
Most of the rest of the cause is the religious squabble within Islam, about who was the right and proper successor to Mohammed. Yes, of course it's silly; it's all irrational, that's my point. After twelve centuries, they're still killing each other about who was #2 in line, and before any Christian joins the scorning, reflect that just a couple of decades ago they were still killing each other in Northern Ireland over the urgent matter of how properly to interpret Matthew 16:13 ff, written about 19½ centuries ago in Greek, reporting a phrase spoken in Aramaic with words now lost to history. My Which Church (if any)? has more.
There remains the matter of where the line is, between state and religion, and as I see it that line varies according to circumstances and to the particular religion. In Islam, as in Judaism, the line has always been very faint; Mohammed was a warrior and combined the office of prophet and commander in chief. So if a war is wanted for state purposes, the chief religious honcho declares it to be for the glory of Allah, their name for god. I notice that with very few exceptions, Islam has always advanced by force, almost never by persuasion. Cassius Clay became Mohammed Ali presumably because he felt black Americans get a raw deal from the white Christian majority; Lisa Halaby converted so as to marry the King of Jordan, and a few others can be found; but when Islam set its sights on Spain it sent not evangelists but soldiers. When it tried to penetrate the Balkans it did likewise, and got turned back at Vienna - again by force. In Islam, religion and state and war are inextricably bound together and the latest manifestation of ISIS, with its demand to Convert or Die, is perfectly typical - even while being condemned by an impressive display of 120 Muslim scholars.
That does not, however, let Christianity off the hook. Normally in recent centuries new adherents have been drawn in by persuasion, by evangelists. Those may appeal more to emotion than to reason, but at least the conversion is an act of will; an individual option. However, cooperation between the Christian church and the state where it's located has been substantial, ever since Constantine gave it special status. Usually the state obtains from the church "moral" support for its policies du jour, though sometimes religious passions run so intense that the roles can reverse; recall the "troubles" of Northern Ireland for most of the period since 1921, in which Protestants and Roman Catholics killed each other - and passers-by - so as to belong, respectively, to the British or Irish State.
So I take the view that all states value any prominent religion as a way of binding residents of their claimed domain to the government, with moral loyalty; a way to perfume the cesspool. Any religion will do, so long as it has many followers. Governments grant privileges to religious leaders - tax exemption for example - and honor and respect, often "establishing" it and even pretending it is superior in status to the government. Thus, monarchs usually get archbishops to crown them, so as to convey the message that they have been appointed by God himself. That nicely answers the question about where the king got his right to rule. In return, the religion is expected to preach that the state is there to be obeyed; Christianity does so explicitly in Romans 12 and 13: "the powers that be are ordained [by] God." It's a sick synergy.
Is one of the two senior to the other? Which is the dog, and which is the tail? - clearly, the state has the commanding rôle, because it has control of the force. It keeps the armory, runs the prisons, operates the gallows. When martyrs were executed by burning at the stake it was no doubt at the insistence of Prods or Papists, but it was a government stake and executioner. When a war was begun by G W Bush he may have sought the Pope's blessing but it was the President, not the Pontiff, who literally called the shots. Like patriotism, religion is a valuable tool for marshaling popular support for war, but it's the state that does the waging. Thus, in the coming zero government society there may be some religion, but there won't be any war.
For further reading on the synergy between state and religion, refer to The Voluntaryist #163, fresh out this month. Carl Watner presents a meticulously researched paper on how religion was used even in Colonial America to bind residents to the State.