It is well-known fact that Adolf Hitler admired Otto von Bismarck. But it was much more than admiration. Hitler considered his Third Reich to be a direct successor of the Second German Empire established by Bismarck.
Consequently, he fully intended to “finish what Otto von Bismarck had started”, including his Kulturkampf – a war (let’s call a spade a spade) on the Holy Roman Catholic Church over the spiritual and ideological control over Germany.
The “finish what was started” also predictably included crushing the Catholic Church in Poland – and institution (correctly) viewed by the Nazis as the bulwark of Polish nationalism (and thus of the struggle of the Poles for the independence of their nation).
However, the whole Kulturkampf thing started many centuries before Bismarck and Hitler. Hence, to understand both (and you can understand Hitler’s Kulturkampf only if you understand the Bismarck’s version), you must understand the origins of the latter. The origins that (not surprisingly) are in the Christian doctrine.
Unlike Islam where the church and the State (i.e. religious and government authority) are inseparable, Christianity openly calls in its Holy Scripture (New Testament) for the separation of Christian Church (i.e. religious authority) and the State (i.e. government authority). The Gospel according to Mark (12:17) is very clear on that:
“Then Jesus said to them, “Give to Caesar what is Caesar’s and to God what is God’s.” (New International Version – NIV)
The authors (compilers, actually) of the New Testament considered this commandment to be important enough to be included into two other Gospels as well. The Gospel according to Luke (20:25) presents this commandment in exactly the same words:
[Jesus] said to them, “Then give back to Caesar what is Caesar’s, and to God what is God’s.” (NIV)
As does the Gospel according to Matthew (22:21):
Then [Jesus] said to them, “So give back to Caesar what is Caesar’s, and to God what is God’s.” (NIV)
According to the Christian Tradition, Matthew wrote for Jews; Mark wrote for the Romans and Luke was a Syrian. Consequently, it is crystal clear that this commandment is addressed (and thus is compulsory) to all nations.
However, the reality turned out to be quite different. Jesus commanded His apostles (and thus, by extension, the whole Christian Church), to convert the whole human population (yes, every single human being on Earth) to Christianity:
The Gospel according to Matthew (28:19-20) states it in no uncertain terms and well beyond any reasonable doubt:
“Go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, and teaching them to obey everything I have commanded you” (NIV)
The commandment about God and Caesar makes it pretty clear that the Church MUST NOT use the power of the state to achieve the abovementioned objective; implicitly saying that its priest, missionaries, monks, nuns, etc. must use sermons, prayers, healing, personal examples (“living the Gospel”, “imitating Christ”, etc.) and other purely spiritual and religious tools instead (i.e. the fear of Hell which was a very powerful incentive for converting to Christianity and remaining a “good enough Christian” at all times).
In other words, Jesus Christ viewed the Church and the State as two totally distinct institutions with the latter taking care of human needs in this world (financial, functional and emotional) and the former – of needs spiritual.
First, and foremost, of course, on making sure that after the death of the physical body every human soul gets at least into Purgatory (at best into the Kingdom of Heaven). And thus is saved from eternal torment in Hell (salvation is job #1, in other words).
Why did Our Lord and Savior (I am a Roman Catholic) Jesus Christ insist on strict separation of Church and State and on the former NOT using the power of the latter in their conversion efforts?
Because He (and God the Heavenly Father, of course) firmly respects the Freedom of Human Will – and thus is adamant about strictly voluntary conversion. In other words, His firm position was that no one should be coerced into converting to Christianity – i.e. by a threat of torture, imprisonment or any other punishment (let alone death).
However, the Church leaders (including the Popes, of course) had a very different idea about what should and should not be done to convert “their neighbors” to Christianity.
And thus save their souls, because until very, very recently, Extra Ecclesiam Nulla Salus (“there is no salvation outside the Christian Church”) was a fundamental dogma of Christianity. “The Christian Church” in this context meant the Holy Roman Catholic Church, of course, because for a millennium and a half Matthew 16:18
“And I tell you that you are Peter, and on this rock I will build my church, and the gates of Hades will not overcome it” (NIV)
were interpreted as referring to only the Roman Church as Saint Peter was the first Bishop of Rome and the head of the whole Church. Which made complete sense given the facts that (a) at that time the whole civilized world was pretty much limited to the Roman Empire – at least in Europe; and (2) to ensure the uniformity of doctrine the Church had to be a highly centralized institution.
Church leaders sincerely believed that salvation from Hell was so important that literally everything and anything was acceptable to achieve that all-important objectives.
In short, that such an important end justified any and all means – even if to save 80% of the souls 20% had to be murdered. Hey, it was OK to kill 80% tom save 20% – if the alternative was to have the whole 100% of the souls go to Hell for eternal (and unbelievably painful) torment.
Besides (let’s be honest), the Church leaders were, alas, very sinful individuals – and already very much corrupted by the power (which was pretty close to absolute) they had in their organization.
As every individual and every organization wants to expand its power, it is no surprise that the Church leaders wanted a secular (i.e. government) power as well – the power over not only the hearts, minds and souls, but over bodies – and wallets – of the population. Top to bottom – from the lowliest peasant to the King.
Hence, it is also no surprise at all that the Church first made the State (i.e., the Roman Empire) to make Christianity an official religion (that was accomplished by the end of the 4th century AD) – which gave the former a pretty serious power over the government.
And then used the secular power to (1) annihilate all other religions – Christianity is the most intolerant faith by far; (2) convert all – or practically all – population to Christianity; and (3) exterminate all dissenters (“heretics”) in the Church, making sure that only the official version of Christianity is preached, taught and followed – everywhere.
However, the government (and the secular elites) – as well as a not insignificant percentage of the population – were not exactly happy with these developments (and outcomes). So almost from the very beginning they began to fight back (consequently, in reality the Kulturkampf had been going on for a millennia and a half).