Robert Bowie Johnson, Jr. may be most famous for his self-published book “Sowing Atheism: The National Academy of Sciences' Sinister Scheme to Teach Our Children They're Descended from Reptiles”, which was endorsed by Don McLeroy, the former chairman of the Texas Board of Education. As you’d expect, this book contains gems like “What kind of monster parents teach their children that they're descended from rodents and reptiles?” and “The hierarchy of the NAS has stolen true science; they are sacrificing our children to their atheism, and at the same time, destroying our children's faith in God.” The book is rather thin on evidence and reason, but then Bob Johnson doesn’t really care for such atheist tricks like ‘sanity’.
He has also written ‘Noah in Ancient Greek Art’ (read that title a second time). Yes, it is a book detailing Noah's role in Greek art as a known historical figure. Yes, that Noah. The Greeks knew the stuff: Noah, Cain & Abel, Eden, and so on – although it has been covered up by an atheist conspiracy. To “shock the Darwinists out of their denial of the overwhelming evidence in Greek art for the reality of Genesis events”, Johnson urges Creationists to “refer to evolutionists as what they imagine they are – Slime-Snake-Monkey-People, or “mutants” (more here and here).
Even the Institution of Creation Research has passed this crackpot by – but he was still found good enough for the Texas Board of Education.
Diagnosis: Ravingly insane crackpot and godbot. His impact is probably limited, but it has evidently and unnervingly shown up in some striking contexts.