I'm an atheist.
It might be worth clarifying your use of "secular", which is often misunderstood. Secular does not mean atheist, it means basically to separate religion (any religion) from the subject being considered. It is used sometimes in relation to the clergy, such as a secular priest. For a society, its context here, secular means to separate the government of the society from religious beliefs (any religion), while protecting the right for any member to believe and practice their own particular religions or lack of religion unhindered (as long as something doesn't break any laws).
A secular society is actually religious people's best friend as it protects them all from finding their society becoming controlled by a particular religion - which might not be their own, or in the US, might not even be Christianity, in the long run.
Atheism is just not having any gods. Atheists just believe in one less god than Christians. It doesn't equate to immorality because in practice there is no difference between the morals and ethics that people follow between the religious and non-religious, and in practice Christians for example only tend to conform to the prevailing morals in the same way that atheists do. If there was a difference, for example Christians would still be practicing slavery in the US, as the New Testament advises slaves not to seek their freedom. At some time in the past people must have decided that that particular principle was outdated. So they were making the same ethical decisions for not having slavery as atheists do, which is to use rational arguments for and against and then making a decision.
In Europe (I'm British) the level of religious beliefs has been decreasing for a long time - in the UK it's around 50:50, with non-religion increasing; while at the same society has been getting more ethical. In the US, approximately 27 people are killed a day by other Americans, which is about 10 times more than most European countries see in a year.
I liked and agreed with most of your comments.One exception was this: "in practice there is no difference between the morals and ethics that people follow between the religious and non-religious, and in practice Christians for example only tend to conform to the prevailing morals in the same way that atheists do."
Humanistic and Christian values are not the same. They are in conflict in several places.
And the way that humanists and zealous Christians come to their moral positions is radically different.
You also wrote, "with non-religion increasing; while at the same society has been getting more ethical." Is that not evidence of something?
And finally, you wrote, "If there was a difference, for example Christians would still be practicing slavery in the US, as the New Testament advises slaves not to seek their freedom. At some time in the past people must have decided that that particular principle was outdated. So they were making the same ethical decisions for not having slavery as atheists do, which is to use rational arguments for and against and then making a decision."
That idea didn't come from Christianity or its manner of determining ethics, which is authoritarian. Ethical values are revealed not worked out using reason applied to compassion. That's the method used in secular humanism: Rational ethics, which was reborn during the Enlightenment.
The Christian method could never have generated the idea that slavery is wrong because it's not in the Bible, a fossilized work. That idea may have been shared by many many Christians, but they didn't get it reading scripture. It was a result of the humanist influence on Western culture superimposed on older Christian ideas and ways. Christianity cannot evolve without outside influences that are not Christian in origin even if some Christians adopt them.
Perhaps the real question is why US Christianity appears so mean spirited and divisive to people outside the US? Is it perhaps that Christians in the US prefer to have someone else to blame for the problems in society?
American Christianity for the most part forged an alliance with the conservatives. Here are a couple of spoofs of what resulted from that:
[1] "You were hungry and thirsty, so I eliminated funding for Meals on Wheels and food banks. You were a stranger, so I vilified you and demanded that you be deported. You were naked, so I called you an evil liberal who hates conservative family values. You were sick, so I repealed your only hope for health care. You were in prison, so I tortured you." - Matthew 25: 42-43 in The Conservative Bible"
And from
https://www.nytimes.com/2017/03/16/...region&WT.nav=opinion-c-col-right-region&_r=0
[2] A woman who had been bleeding for 12 years came up behind Jesus and touched his clothes in hope of a cure. Jesus turned to her and said: “Fear not. Because of your faith, you are now healed.”
Then spoke Pious Paul of Ryan [refers to conservative House Speaker Paul Ryan]: “But teacher, is that wise? When you cure her, she learns dependency. Then the poor won’t take care of themselves, knowing that you’ll always bail them out! You must teach them personal responsibility!”
They were interrupted by 10 lepers who stood at a distance and shouted, “Jesus, have pity on us.”
“NO!” shouted Pious Paul. “Jesus! You don’t have time. We have a cocktail party fund-raiser in the temple. And don’t worry about them — they’ve already got health care access.”
Jesus turned to Pious Paul, puzzled.
“Why, they can pray for a cure,” Pious Paul explained. “I call that universal health care access.”
Jesus turned to the 10 lepers. “Rise and go,” he told them. “Your faith has made you well.” Then he turned back to Pious Paul, saying, “Let me tell you the story of the good Samaritan.
“A man was attacked by robbers who stripped him of clothes, beat him and left him half dead. A minister passed down this same road, and when he saw the injured man, he crossed to the other side and hurried on. So did a rich man who claimed to serve God. But then a despised Samaritan came by and took pity on the injured man. He bandaged his wounds and put the man on his own donkey and paid an innkeeper to nurse him to health. So which of these three should we follow?”
“Those who had mercy on him,” Pious Paul said promptly.
Jesus nodded. “So go ——”
“I mean the first two,” Pious Paul interjected. “For the Samaritan’s work is unsustainable and sends the wrong message. It teaches travelers to take dangerous roads, knowing that others will rescue them from self-destructive behaviors. This Samaritan also seems to think it right to redistribute money from those who are successful and give it to losers. That’s socialism! Meanwhile, if the rich man keeps his money, he can invest it and create jobs. So it’s an act of mercy for the rich man to hurry on and ignore the robbery victim.”
[snip]
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Humanists would repudiate all of that, which is why I said that humanistic and Christian values are in conflict in several places. Frankly, that cannot even be called moral. I sense from you comments about American Christianity that you tend to agree.