John Locke famously argued that atheism/atheists ought not be tolerated in a religiously free society:
Lastly, those are not at all to be tolerated who deny the being of a God. Promises, covenants, and oaths, which are the bonds of human society, can have no hold upon an atheist. The taking away of God, though but even in thought, dissolves all; besides also, those that by their atheism undermine and destroy all religion, can have no pretence of religion whereupon to challenge the privilege of a toleration. As for other practical opinions, though not absolutely free from all error, if they do not tend to establish domination over others, or civil impunity to the Church in which they are taught, there can be no reason why they should not be tolerated.
While this makes me uncomfortable, I am reminded of what Rosenberg wrote, of atheists, in his book The Atheist Guide to Reality:
The interesting thing is to recognize how totally unavoidable [the answers to the questions below] they are, provided you place your confidence in science to provide the answers.
Is there a God? No.
What is the nature of reality? What physics says it is.
What is the purpose of the universe? There is none.
What is the meaning of life? Ditto.
Why am I here? Just dumb luck.
Does prayer work? Of course not.
Is there a soul? Is it immortal? Are you kidding?
Is there free will? Not a chance!
What happens when we die? Everything pretty much goes on as before, except us.
What is the difference between right and wrong, good and bad? There is no moral difference between them.
Why should I be moral? Because it makes you feel better than being immoral.
Is abortion, euthanasia, suicide, paying taxes, foreign aid, or anything else you don’t like forbidden, permissible, or sometimes obligatory? Anything goes.
What is love, and how can I find it? Love is the solution to a strategic interaction problem. Don’t look for it; it will find you when you need it.
Does history have any meaning or purpose? It’s full of sound and fury, but signifies nothing.
Does the human past have any lessons for our future? Fewer and fewer, if it ever had any to begin with.
Aside from the hilarity of an Atheist writing ‘ THE guide to reality’ for other atheists while decrying as stupid those who believe in sacred literature, in what you read above there are two major incoherencies:
- If you can learn nothing from the human past, then you can learn nothing from science for every experiment was done in the past.
- If there is no difference between any opinion, moral or otherwise, and no meaning to human history, then it makes no difference to believe in illusions or not, so the book is frivolous and without meaning.
But aside from atheism’s ability to inject such incoherencies into one’s thoughtspace, it also does precisely what John Locke feared: it devalues the keeping of promises because the reason to be moral is that “it makes you feel better than being immoral.”
There is no valuation attributed even to the individual life nor to the project of civilization. Even evolution, for all its transfer of data and information and the thousands of years it took for luck to yield beings who experience the universe as a series of ecstasies and horrors, has no point and the information given to offspring through culture and DNA has no meaning (this is false on the surface because our cells find plenty of meaning in DNA).
Anyway, if human contracts, human civilization, and human life have no meaning in this worldview, then Locke was right to be suspicious of those who held it.
 Alex Rosenberg The Atheist’s Guide to Reality: Enjoying Life Without Illusions (Digital Edition), 22.9/669.