No-one "teaches" kids to be atheists. Sensible parents show their children the importance of never trusting what information anyone tries to give them unless the information can be supported by evidence, and they help them to work out what is true evidence and what is false evidence.Telling a child that they shouldn't believe in God is just as bad as telling them that they should believe. The main difference here is that thinking atheists, unlike believers, don't indulge in these practices. Good atheists want their children to be entirely free to make their minds up in an informed way. I suppose there are some good believers who also think that. That is a highly respectable position. Unfortunately, it seems to be an extremely difficult one to be true to.