Association fallacy

Association fallacy, or "Guilt by Association", is when two concepts or things are equated, or have equal attributes, due to a common held attribute, when the comparison is not true. This error arises through casual thinking, since by nature, we tend to categorize what we perceive from reality to a high degree. To a degree, it's similar to a "correlation does not equal causation" error. Some examples are:

• Bob's car is fast. Bob's car is also red. Therefore, my red car is also fast.
• Fred is smart. Fred is a Christian. Therefore, all smart people are Christian.
• Chocolate is made from organic compounds, and is tasty. Poop is also made from organic compounds, and is therefore, tasty.

During debates, atheists will hear a number of these examples:

• Stalin was immoral. Stalin was an atheist. You are an atheist, like Stalin, and therefore are immoral too.
• Religions are people that get together and discuss common topics. Your atheist community gets together and discusses common topics, and is therefore just another religion.
• People of faith are fervent in their beliefs. Bob, as an atheist is fervent about his beliefs, and thus has faith too.