I am just approaching the end of a term spent studying Protestant theology in Europe and America in the 19th Century. It has been fascinating, but only in the way that a documentary about the Titanic or a train-wreck might be fascinating. The 19th Century sees the complete marginalisation of orthodoxy within Protestant theology, and a move toward man as the measure of all things which is utterly destructive. By the time we get to the First World War, we are faced with the terrible sight of German theologians enthusiastically supporting the Kaiser's war, and theologians across Europe not only failing to protest the war but actually talking it up as a war for Christianity and civilisation, as if these two were the same, as if they were both in desperate danger, and as if leaving the youth of the continent dying in the mud would save them. And that was not a blip; it was the logical end point of the mainstream of theology over the previous century.
What went wrong?
Well, firstly, in the 18th century, theologians argued that Christianity was reasonable, and therefore ought to be believed. That doesn't sound like the precursor to a disaster; the whole exercise was in fact considered as necessary to stave off disaster and to equip Christianity to survive the Enlightenment. But at some point there was a switch. Instead of arguing that the whole of Christianity was reasonable and therefore to be believed, suddenly theologians were arguing that only what was reasonable was to be believed, and therefore Christianity must be subjected to a critique that removes everything reason cannot accept. This was, in many ways, just a frank acceptance that the 18th century apologetic project had failed. This failure was not immediately obvious. But as 'what can be rationally believed' gradually shifted, the ground upon which the 18th century theologians had taken their stand was eroded and eventually destroyed. A bare kernel of 'Christianity' was left.
Secondly, theology failed to assert the transcendence and immanence of God. Kant stressed the transcendence; Hegel in protest stressed the immanence. The former made God inaccessible, and was not hugely attractive to theologians (although philosophers liked it); the latter seemed much more likely to provide theology with what it felt it needed - a plausible philosophical basis. But for Hegel God was locked inside the system of the world, and especially human culture. The logical development of his thought was the 'History of Religions school', which sought to trace the development of religion in history in order to see the revelation of God. Protestant Christianity was seen as the highest point (absolute religion for the likes of Schleiermacher and Harnack; the best so far for Troeltsch). In this movement, revelation came to be identified with cultural development. It comes as no surprise that a theologian like Harnack, who wrote that Protestantism was the genius of the German national spirit, would ultimately fail to criticise the War. (In fact, he signed a manifesto in support of it).
What do we have to learn?
Firstly, to be suspicious of our felt need to make Christianity rationally acceptable to those around us. We could succeed in this apologetic task and still be putting down a time bomb in the church which will be devastating in a hundred years. In particular, we need to remember that there is not some timeless standard of rationality to which we can appeal; what seems reasonable to someone today may not seem so reasonable in a few decades. So we mustn't rely too much on the rationality of those around us.
Secondly, we need to be on our guard against moving with the times. Revelation always stands over against culture and critiques it from its own place. Whenever anyone discards a piece of Scriptural teaching on the grounds that it is old fashioned (and this happens often, under different guises), we need to ask whether the surrounding culture has been allowed to smother the voice of the apostles and prophets.