I'd go for the Flying Spaghetti Monster badge instead. It will convey your atheism to like minded individuals, but likely will not be understood by your typical Bible banger.
It will certainly be seen as an alternate to the abundant Jesus fish on every other car, but less likely to get your car vandalized.

It's amazing how many loving Christians have no problem vandalizing a stranger's car due to a decal... Or starting a fight, or causing problems with you superiors, etc.

Religion is all about creating reasons to hate other people. Atheists are roughly tied with Muslims as the most hated minority. Identifying your beliefs to other drivers is also dangerous while driving. Our society is simply not mature enough yet, not to expect a bad outcome.

Probably the better question is: In what reasonable ways can atheists teach their rationality?

I have a specialty SC license plate designed by a Free Thought group that has the slogan "In Reason We Trust"

Risk assessment should probably include how much your car insurance deductible is, and if your policy covers vandalism.
Living where you do, it's probably a good idea to expect some sort of retaliation for expressing your Constitutional right to self-expression.

I think you should refrain from placing anything on your car identifying yourself as an atheist... It seems there is the highest potential for vandalism to your car.

Be careful...there is always an idiot around that may want to hit your car because you are a sinner

Just get that simple "A". Likely only other Atheists will recognize it.

I’m outspoken w my atheism person to person. Bumper sticker? No, it invites the religious to do gods work and fuck up my car.

Just be proud of who you are and do not risk your vehicle. I did just that a few decades ago when I traveled W Virginia. My car was scratched, dented and someone put dog poop all over it. Not worth it. It just made me mad is all. Not what I want to achieve

If you don't care that the christians will deface your vehicle you should go right ahead. I would however, suggest something more subtle like a fish with legs.

I think it’s more important for people who know me to identify someone they like as an atheist, than to have complete strangers assume things about me.

I'd say better not. Even here in Australia, where there are heaps of non-believers, I'd be reluctant. Religion (or lack of it) is something we don't advertise much.

I'm in general against putting stickers on cars, for one they're tacky and for another it gives lunatics an excuse to target your car for vandalism. Just keep your car clean and nice.

Try Open minded.

As a fellow Texan.......DON'T DO IT!

the rebel in me would say yes go ahead. however, you maybe need to assess the risk in doing this!

No. I like having tires with air in them and as few scratches as possible on my vehicle. The godly often tend to be destructive.

I put an evolve fish on all of my vehicles. You can find them here - [evolvefish.com]

No too many religeous fanatics out there you would be a target for insults and maybe personel damage to self and car be careful yes we can hold our own but don't forget many are brainwashed into believing their religion is true and the best

Just be yourself. You have nothing to prove to those theist. If you want a bumper sticker then brandish one. You are free to do so. Who cares what they think. If they damage your car then they are responsible for the damages and any criminal charges. Your First Amendment right does not get revoked if you work in any particular job.

Are you rich? Do you know how much auto body repair cost? I'm sorry to say that we have to keep our Atheist pride to ourselves in 'Murica.

Why do you feel a need to be so "in your face" about this subject. I would most likely decide to smile inwardly at the hypocrisy and soldier on. Your sign would more than likely bring a caravan of fanatics wanting to convert you.

I voted yes because I think it's the right thing and you should. I also think I should though an I don't. I have a job and kids and they go to school and their friends have parents... I'm just not sure it's worth it.

No vote, I don't do stickers or decals, no tattoo or piercing... I am.... Au Naturale!!! And why not.... so my vehicle.

If they can, you can.

It shows how toxic religion is if you feel afraid of them.

You have as much right to display a sticker as they do. Be brave.