Bruce Charlton, who is usually wise except when his religion gets in the way of reality, argues that the origins of the left are not in Christianity, but rather in secularism, that Christianity became corrupted into leftism by becoming secular, rather than secular because corrupted into leftism.
He is wrong. Christianity really is to blame. First Christians became leftists, then, being leftists, became secularists.
Christianity became corrupted, then became secular because corrupted. It did not become corrupted because secular. It was corrupt when it opposed New Testament style marriage, slavery, and supported the emancipation of women.
To argue that secularism caused the rot, you have to put the rot beginning around 1950, just as to argue that Jews caused the rot, you have to put the rot beginning around 1950, but the problem set in much earlier. Bruce Charlton wants to argue that secularism set in many centuries ago. It did not. In the early twentieth century, the ruling anglosphere left was still Christian.
Even back in the beginning Christianity was always a little bit leftist relative to the egoistic morality of Aristotle (who argued virtue is cultivation of one’s own excellence) and Xenophon (who took for granted that virtue is to be honest and peaceable to those who are willing to be honest and peaceable, and virtue is to rob, rape, and slaughter in a courageous and manly manner those otherwise inclined)
Thus, when Christians pursued power through being holier than thou, they promptly proceeded to become lefter than thou.
The Puritans, from the execution of the Charles the first to the restoration of Charles the second were Christian, their major defect being that they were holier than thou. They were also leftists and the precursors of twenty first century leftism.
During that period they raised the age of consent, made divorce easier, and prohibited marriage as a sacrament. Marriage became completely secular, resulting in brief and symmetric marriage vows. No more did the wife promise to love, honor, and obey, and the husband promise to love, honor, and cherish. No more was marriage accompanied by a long lecture on the New Testament definition of marriage, presented in the presence of all the relatives and friends, including numerous patriarchs and alpha males willing and able to enforce that doctrine. (All this was reversed in the restoration).
The puritans did not like the New Testament doctrine that marriage was an irrevocable commitment to, among other things, sexually gratify one’s spouse regardless of whether you felt like it or not. They did not like people having fun, and particularly did not like males having fun, hence did not want a license for men to have fun to be a sacrament, did not want it provided with social enforcement by the congregation and spiritual enforcement by the priest. Puritans wanted to emancipate women because they were never very happy with men humping women.
The puritans were and are leftists, undermining society, killing the King, suppressing the display of excessive wealth, undermining marriage, and being general uptight killjoys who get offended by just about everything. Being offended is a power play. They are holier than me so supposedly I have to do what they say.
The puritans are what you get when people compete for power by competing to be holier than thou.
When priests get the upper hand over nobles and soldiers, they promptly start competing to be holier than thou, and in the process they pervert and corrupt their religion.
Christianity did not become corrupted by secularism. It became secular due to corruption – they pursued supposedly noble goals that were incompatible with the New Testament, in particular the suppression of slavery and the emancipation of women – noble goals that somehow wound up advancing their political power.
Abolishing slavery with fire and sword is arguably a noble cause. Defenses of slavery and justifications of slavery fail in practice to apply to all slaves, though they apply to some slaves. But it is a cause entirely incompatible with the New Testament, which mildly encourages Christians to free their own slaves, and to look the other way when runaway slaves pass by, but forbids slaves to run away, and forbids Christians to interfere with the property of slave owners, even if they do not have to too actively assist in enforcing the property rights of slave owners. The Old Testament prohibits wrongful enslavement, but implies that debt slavery and the enslavement of defeated populations that stubbornly and incorrigibly refuse to surrender is OK.
When Christians adopted the cause of forcibly ending slavery, it was entirely predictable that they would soon demote Christ the Redeemer to Jesus the community organizer. A more martial religion could have adopted the cause of forcibly ending slavery, and still remained true to itself. Christianity could not.