An even tighter guess is THE NIGHT GOD SCREAMED (1971)
http://www.imdb.com/title/tt0067488/ This one is very obscure but read through the user reviews on IMDB and you'll notice some striking similarities: it's got a Jesus-looking lead hippie freak, a family under siege, and, closest to your memories, a twist ending where the little girl kills the hippie leader (with a knife, not an axe).