If I said that I'm an atheist in your nation?

[Madohomuland]

Impossible. You'd never have become a citizen without believing in Madoka.

[Cerinda]

You would be welcomed.

[Aurevbush]

As freedom of religion exists in Aurevbush, nothing would happen to you.

[Athonuna]

You might get a few weird looks from children and the occasionally "They don't believe in God, mama?", but freedom of religion protects you. The worst you'd get is "I'll be praying for you, dear."

[-Astoria]

'Um, that's fine - no need to bother yourself about it.'

[Alpes a Septentrionali Imperium]

You probably wouldn't have a good time as most of the population is religious and there is an official state religion

[Minachia]

You'd probably get strange looks and be viewed with suspicion, but other than that you're probably fine.
Apart from our massively religious Christmas, Holy Week, Easter, and Pentecost celebrations, among other holidays.

[The African Emirates]

So what? Literally everybody here is atheist. You ain't special.

---

-Pretty much every citizen of The African Emirates

[Ravennog]

You would receive a standing ovation from the Ravennogan people

[United States of Americanas]

Absolutely nothing would happen. You’d be treated the same as any other citizen by the government.

That said the government will not protect you from religious people looking down their noses at you.

Freedom of speech guarantees you the right to speak your thoughts without worry of government consequences however you are responsible for handling any negative responses from other people.

The vast majority of our nation uses the Unity religion and therefore respects atheists rights to choose not to believe in a higher power however there is a small bloc of weird Christians that you should stay away from unless you want to get into religious arguments.

[New Ciencia]

You would get some rather strange looks; most of our population is atheistic.

[The Plantain Republic]

Half the population would shrug it off and walk away. The other half would tell you, “I thought you were Kaifunasian”.

[Honningberg]

It would be nothing new in a country governed by nontheistic Luciferians and atheists. Some who are believers in the supernatural would likely have a problem with you not believing in (their) god. They may openly disagree in civil conversation, or otherwise mutter among themselves.

[Nation of Valkia]

You would be looked down upon if you were an atheist. Valkia's national religion is Catholicism and anyone who doesn't follow the national religion is viewed with suspicion.

[Saint Arsenio]

You'd be treated just like anyone who was our National Religion, Christianity. You'd be treated no less.

[Risusol]

You'd be treated very well! In fact, most of our people is atheist too.

[Lanorth]

Your beliefs would be respected and you would be treated normally without change.

[Azlaake]

we wouldn't care, we're all inclusive

[Communist Zombie Horde]

You'd be breaking the law-not certain that means anything if you still show up to church and the people with guns don't have a target on your back already.

[The Cow and Dairy Isles]

Our government wouldn’t care but some angry farmers would throw old cheese at you and drown you in milk

[Melondonia]

As long as you weren't saying that to condemn those who were religious/claim that your religion (or lack thereof, in this case) automatically made you superior to others, you would be treated no differently. At worst, you'd probably hear a "kids these days..." under somebody's breath.

Freedom of speech, Freedom of Religion... and all that jazz.

[Grotesque Spore Creatures]

You'd be in the 100% majority, since Spore Creatures don't even know what a "religion" is.

[Valloire]

No one would really care, unless you're rabid and foaming at the mouth about it.

[Great Mojave]

"Dude, no talking at the library!"
"Um, ok."
"We're trying to play blackjack over here, do you mind?"
"oh cool me too"

[Savresia]

Since %87 of population is non-religious, it is quite common.