Dan thinks we should mostly credit atheists not Christians with liberalisation in the US. let's see about that. lets start with the biggest, greatest, most important bit of liberalisation: freeing the slaves.
a quick google search and here's some info
The word "slave" was never used to describe a legitimate condition in the Hebrew Bible. Instead, to describe the immoral thing it is, terms such as "made . . . to serve with rigor" and "hard bondage" (Exodus 1:13-14) were used to describe the concept
Hmm, apparently there were religious arguments against slavery. I wonder who made them...
Pursuant to English and U.S. constitutional and criminal law, slavery was illegal and unconstitutional. Kidnaping, murder, robbery, and rape (the basic features of slavery as it existed) were illegal. Some religious Northerners said that slavery was therefore a sin. A number of men had written books, articles, and even set up newspapers to oppose it, and get it abolished. But they were not having success, as most Northerners felt unaffected by slavery. Any sin, it wasn't them doing it.
So sounds like most Northerns thought it was a sin. Anyone who thinks it's a sin is A) religious B) pro-liberalisation on this issue
in 1850, slave holders had Congress pass a law (the Fugitive Slave Act) making following those biblical principles a crime, "aiding and abetting" escapes. This law made Northerners such as Mrs. Stowe feel that they were now being forced to participate in the sin. So the law was widely defied as unbiblical and unchristian.
pro-slavery laws were opposed because they were unbiblical and unchristian. QED?