Entryism: infiltration tactics explained

We're at the end of Stuart Wexler's book, Chasing Shadows. It has been an interesting ride through early inceptions to the present. It gets scary at times. It gets you thinking about "How has this happened in our country?" "It keeps rearing its ugly head and penetrated our local, state, and Federal governments" not for the good of all. It seems to get worst. Will we be able to pull out of the Abyss?