In his speech “Why I’m not a Christian“, the philosopher Bertrand Russell is completely willing to state wild fiction as if it were sober truth:
You find as you look around the world that every single bit of progress in humane feeling, every improvement in the criminal law, every step toward the diminution of war, every step toward better treatment of the colored races, or every mitigation of slavery, every moral progress that there has been in the world, has been consistently opposed by the organized churches of the world.
If this were true, historians would report that the nineteenth century deists led the abolitionist movement, rather than Christians. We’d find that charities in our present time would be overwhelmingly secular, rather than overwhelmingly religious. We’d find that the early Christians were less, rather than more, open to racial mixing than the pagans. We’d also find that no real social progress was made until secularism became a notable force in society, rather than finding otherwise.
That such a blatantly, factually false statement can be made (and continues to be made) by persons who claim to base their positions on facts and reason is something of a scandal. As much as cultural stereotypes lend enough rhetorical plausibility to this claim, no one doing so can be relying on science or following the evidence where it leads.
But, even granting the highly dubious claim that churches are inherently resistant to change in the moral consensus (which seems to be Russell’s position), three issues remain:
First is the question of whether “opposition” can be assumed even when it is a tiny minority of churches. That seems to be Russell’s basis for making this claim, but this would definitely open him up to accusations based on the behavior of a tiny minority of atheists.
Second is the fact that Russell offers no standard of “progress”. He needs to explain why his view of progress is superior to the view of the churches he criticizes. He does not do so here, and I’ve not heard an answer to this problem from the New Atheists.
And third is the simple point that there is no logical way to get from “churches have impeded progress” to “Christianity is false”. If anger at the wrongs of churches is truly a reason why Russell rejected Christianity, then he is simply admitting to a certain amount of irrationality. Christ is not judged by the actions of the church. Rather, we are judged by him.