A few bumper sticker/pin slogans I like:

Adam was a rough draft

Freedom is the distance between Church and State

Against abortion? Then don't have one

Atheism cures religious terrorism

My job is to comfort the disturbed and disturb the comfortable

DARE to think for yourself

Diversity without division

Doing my part to piss off the religious right

Don't pray in my school; I won't think in your church

Don't believe everything you think

Equal rights are not special rights

Faith is believing what you know isn't so

Focus on your OWN damn family

Freedom of religion means any religion

God is too big to fit inside one religion

God is just pretend

God protect me from your followers

God was my copilot but we crashed in the mountains and I had to eat him

Hatred is not a family value

I believe in life BEFORE death

I don't mind straight people, as long as they act gay in public

If going to church makes you a Christian, does going to the garage make you a car?

If only closed minds came with closed mouths

If they outlaw teaching evolution only outlaws will evolve

If you are against abortion, get a vasectomy

If you want a country run by religion, move to Iran

If you're born again do you have 2 belly buttons?

It's your Hell, you burn in it

The media are only as liberal as the conservative businesses that own them

Militant agnostic: I don't know and you don't either

Minds are like parachutes: They only function when open

No one is free when others are oppressed

No Gods No Masters

No special rights for Christians

Religious groups should stay out of politics or... be taxed

Well-behaved women rarely make history

Why be normal?

Atheism is a non-prophet organization

At first they burn books; eventually they burn people

The Christian right is neither

Christians aren't perfect; they just want you to be

I think therefore I'm dangerous

I wasn't created in your image of god

I've got nothing against God; it's his fan club I can't stand

If Gay and Lesbian people are given civil rights, then everyone will want them

More humanity, less corporate greed: it does a society good

Subvert the dominant paradigm

Think again