Tell them to STFU

I tell them i like mythology though i tend to stick with Greek/Roman, & Norse mythos. Then i go into all the virgin births, gods hung on trees/sacrifices, resurrection stories, the similarities between christianity & egyptian mysticism...once they start getting pissed off, I smile, asked them to forgive me & spend the rest of the trip reading with my earbuds in.

Shoot him if you can get away with it.

I think they would be quite sorry to start this conversation as I will shake their faith.

Same thing I do every time someone starts spouting bullshit about a loving god. Whip out my phone and start playing cartel execution videos. If they persist it is to the tor browser and live stream of something worse we goooo

I will politely tell the other party my view on religion and get them so upset that I'm not a beliver that they go silent. Then I smile and rest uncomfortably while the kid behind me kicks my seat and the person in front reclines their seat crushing my knees.

It would depend on the person and my impression of them as well as their persistence. I could ask a thousand stupid, annoying questions, pretend to not speak English, debate them, or if I'm in a bad mood and they come across poorly in every metric, I will be a complete asshole.

Tell them I’m a atheist and I don’t believe in their bullshit.

loudly pass gas several times.

I have a wonderful talent for falling asleep after takeoff. There is no faking the sleep. I miss meals and don't hear screaming babies. I LOVE flying!

I'm sorry. I'm just not into cults, but our laws clearly indicate that you're allowed to follow yours.

Oh, I should be so lucky. I will start on the whole Nrse mythology, from Yggdrasil and the eight worlds right through Odin and his quest for knowledge. Their eyes will flow over when i tell them how Odin hung himeslef from a tree, upside down and sacrificed one of his eyes to be able to learn the runes.And if they are still paying attention, I will tell them the story of the Three Norns, the most powerful beings in the universe- women from the world of ice giants. And there are still so many tales to tell, Ragnarök, Valhalla, Fafnir and Jörmundandr, the world snake.
Are your eyes watering yet?

I would attempt to explain and if all else fails tell them to shut the fuck up.

I would order more champagne then dive into a conversation to find out what makes them tick. Also, order more champagne.

Probably something the TSA will frown upon...

Tell them firmly to shut up as I'm an Atheist who has already been on the alpha course and found nothing in it to change my views on religion.

If that does not work then it will depend on what sort of mood I'm in.
If I'm feeling benevolent, then I'll say I have already seen the second coming on TV. It happened in Manchester back in the early 2000s, when the Son of God made it permanently noon at the Maine Road football ground. (This was the plot of a 2003 British TV drama series.) I have done this with Jehovah witnesses when they annoy me on my doorstep. ?

If I’m feeling particularly mischievous then I'll debate them and see if I can shake their belief and rock their worldview to its core so as to de-convert them. Come to think of it, this might have been the other reason my university’s Christian society described me as the Anti-Christ back in the day. Praise indeed ?

If telling them that I'm an atheist doesn't shut them up, and the flight attendant doesn't move me into First Class to get away from them. they're going to hear exactly why their entire belief system is completely full of shit.

Tell the flight attendant to see if there is a physician on board. We're going to need one soon.

Fake sleep and try to really sleep.

I think I'd threaten violence