I saw this on google video today. This is an exploitation movie in the true sense of the word. This gets mentioned on this forum every now and then because of it's heavy handed anti-Communism but it's so over-the-top and violent that it's a dark comedy really. Apparently there's a spirtual sequel called The Burning Hell. Has the same preacher with the same bullshit. It was released in 1974, three years after IFTYWWHD? and it's on youtube in several parts. Might check that out too.
haven't heard about this at all, thanks for the mention