We’re often told there was no separation of church and state in medieval Christianity, and to an extent that’s true. Christian thought influenced political decision making. The church legitimated monarchs; secular kings granted lordships to bishops; popes claimed the right to depose monarchs, and there was an ongoing contest between the religious authority of the pope and the secular authority of the Holy Roman Emperor.
But — and this is a big but — there was a very clear divide between church law and civil law, which reflected a distinction between an individual’s spiritual well being on the one hand, and the person’s freedoms and responsibilities before the law on the other. In some Christian lands that distinction became so sharp you’d hardly guess this was the time before or during the crusades. In England, for example, common law derived from local judges, and no priest or church figures were involved in it. Or in Castile (the Christian part of Spain), where local tradition-based law was written down in the fueros (town’s rights), confirmed by the crown in royal charters, and administered by popularly elected local mayors — with again, no priestly or church involvement in the law’s creation or application.
Everywhere in Catholic Europe, civil law was administered by the laity. Priests stuck to their own law: canon law. That wasn’t true in the Islamic world, where sharia law was both religious and civil without distinction. Religion was the law (and still is today in many Islamic countries), which meant that Islam was the law. Sharia pervaded every aspect of life, from a the private to the public, and Muslim clerics ruled over the daily life of the Muslim population. The public spaces (in this so-called “golden age” of Islam) were regularly patrolled by religious functionaries who had the powers of a judge over the people’s personal, social, and commercial behavior. One looks in vain to find an equivalent judge in medieval Catholic Europe — that is, a dispenser of the law who was also an expert in the New Testament and could officiate, lead prayers, and deliver homilies. Such priest-judges did not exist. And because common law evolved independent of royal or priestly power, it could have a politically liberating effect (long before the Magna Carta), not least in the ideas of people’s freedoms and responsibilities before the law. Freedom, in this sense, was wholly antithetical to sharia law in the Muslim world.
Something to bear in mind, the next time you hear that “church and state were inseparable” in medieval Europe. As far as the statement goes, it’s true, but few people understand what that means and what it doesn’t.