About two years ago my roommate told me a story about how his mother had gone to a catholic school in her youth, and all the different things that they would teach as facts. One of the things that she was told was that being an atheist is the same thing as being a Satanist, and that it meant that they worshiped Satan.
An atheist and a Satanist being the same thing couldn't be farther from the truth. The definition of atheism is the lack of belief of one or more Gods. There are many misconceptions about atheism other than its like being a Satanist. One thing that many people believe about atheism that isn't true is that they think that atheism is a religion. Atheism is the exact opposite of a religion as the followers of atheism do not believe in a God or higher power of any type.
Another misconception about atheism is that it's filled with people that have nothing to be happy about in life because they don't have an afterlife to look forward to. Atheists have just as much to be happy about as everyone else, though they don't think there is a heaven to go to when they die they can still be happy about experiencing life on earth. A very common misconception about atheists is the belief that atheists want to destroy religion or convince everyone else to be an atheist. Though there may be some atheists that think this way, it isn't what it means to be an atheist, and it isn't a widely accepted view that atheists have.
A view about atheism that kind of goes with the last misconception is the belief that atheists don't respect other people's religions. Though there are atheists that don't respect other people's religions, doesn't mean that it is common for atheists to not show respect for different religions. Disrespect for other people's religion is actually seen as negative behavior in both religious people and non religious people and is widely frowned upon in the United States.
Some people also believe that atheists only consider themselves atheist because they are misinformed about other religions. There are many atheists that were born in religious families and had to go to church and or private religious schools thought taught about the family's religion. There are also many atheists that have read canonical scripture at some point in their life, or may have even taken a world religion class to learn about many different canonical scriptures from different religions.
There are many misconceptions about atheism and what it means to be an atheist, but we all need to remember that the definition of atheism is the lack of belief in one or many Gods, and that is all, there is nothing more that constitutes someone to be an atheist. Someone can't be a better or worst atheist than other person, or practice atheism more devoutly than someone else when the belief behind atheism is just a lack of beliefs.