Like tattooing nothing? I think I did that.

Only limited by your own imagination

Something simple.

Maybe a diagrammatic representation of biodiversity?

I've always thought that those old school ink line drawings of fossil type specimens from old paleontology text books would make great tattoos - especially Ammonites and Trilobites.

I'd love to talk a xtian into getting a Leviticus 19:28 tattoo.

[biblehub.com]

The logos of the many atheist, humanist etc movements. Some nice citation, some basic science like hydrogen atom or a fundamental equation like the Maxwell ones that represent human knowledge.
But there is not a single atheist symbol, no movement could put us together for enough time to create an unique identity.
Even if it is a myth, I am thinking a lot about tattooing Prometheus, if you read Prometheus Bound from Aeschylus you will understand his position about freedom and knowledge.

My only thought is that’s the last thing I would want to get a tattoo of, but to each their own.

Maybe this?

[images.app.goo.gl]

Personally, i don't have any tattoos. You don't put bumper stickers on a Ferrari.

The Flying Spaghetti Monster?

Don't have it on your bucket list, it will really hurt there.

Tattoos typically don't go on a bucket list. They go on your skin.

Something from the Periodic Table, spelling something out?
A cross with a "not allowed" symbol, like a sign?
The possibilities are endless......

You might consider this:

9:3:3:1

It's the ratio of phenotypic combinations that Mendel got in the F2 generation in his classic dihybrid cross experiments. The underlying significance is that this ratio illustrates in microcosm the genetic recombination that occurs as a result of sexual reproduction. Sexual reproduction, it turns out, is a great driver of diversity, and diversity is the raw material that natural selection acts upon in biological evolution. So if you wear that number on your body you are celebrating sex, diversity, and evolution, and there is not even the slightest reference to any religion!

Contact Kathleen at Mind Magik Tattoo in Hale Michigan

Here's an idea

I think the Avengers tattoo looks like an Athiest or Agnostic tattoo.
[polygon.com]

Could just go with a science based tattoo. I saw one that was a circle where one half was the solar system and the other way the evolutionary tree.

I would think the best would be your individual idea of why Atheism holds meaning for you and something not to overt. Unless you are more interested in it as a in your face statement for others. No judgment either way just curious as to which is more what your going for?

Sure I have seen them. They are a tattoo of nothing at all.

Google is our friend: [religioustolerance.org]

We all atheists and agnostics know our symbol tattoo, and we all have it in our arm. Even though you didn't know, you have one, pull your sleeve and you'll find it: It's our god!...nothing! ?