In To Kill a Mockingbird, what does Atticus think about the Ku Klux Klan?
As you might expect, Atticus is no fan of the Klan. However, he also seems to be either surprisingly uninformed about the KKK (a very un-Atticus-like characteristic, since he is historically, politically and socially savvy on most subjects) or else he is deliberately trying to mislead Jem (also unlike Atticus) on the subject in order to put him at ease. The subject of the Ku Klux Klan comes up in Chapter 15, when a "gang" of people meet in Atticus' front yard. When Atticus explains that it wasn't a "gang," Jem speculates about the Klan. Atticus tells him about one appearance the KKK made many years before when they
... paraded by Mr. Sam Levy's house one night, but Sam (said) ... he'd sold 'em the very sheets on their backs. Sam made 'em so ashamed of themselves they went away."
Atticus probably sensed that Jem and Scout were worried about him, so Atticus told them
"Way back about nineteen-twenty there was a Klan... The Ku Klux's gone... It'll never come back."
How wrong Atticus proved to be. It is obvious that there must have been little or no Klan activity in the Maycomb area at the time, or Atticus would not have been so easily fooled. Again, however, he may have only been trying to calm his children by hoodwinking them with a white lie (no pun intended).
Atticus minimizes the power of the Ku Klux Klan when Jem brings up his worry that the group of men that has gathered outside the Finch home are Klan members. To Jem and Scout, this gathering of men marks the start of the "nightmare" that becomes their lives when Atticus takes the case of Tom Robinson.
Atticus denies to Jem that the men outside could be Klan members, and it is true that he might be doing so to keep the children from feeling scared. Another possibility that explains Atticus's choice involves Atticus's own hope that Maycomb community members would never get involved again with such an organization. Atticus is a pragmatic person, but he is also idealistic, and his response to Jem could reflect his optimistic belief that the Klan cannot possibly exist in their world. After all, Atticus takes the case of Tom Robinson believing Tom was innocent and that justice might just have a chance of prevailing.