Author John Stanley gave the film a negative review, stating that the film "only comes to life with the appearance of a zombie-like creature that cannot be killed, and the efforts of hero and heroine to do the monster in." In his book The Complete H.P. Lovecraft Filmography, author Charles P. Mitchell stated that "although marketed as an explicit horror film, it is actually a rather thoughtful picture rather than a gorefest. Unfortunately, it is overlong, and occasionally bogged down with too many irrelevant subplots. The script stresses the mystery elements of the story, making its revelations in piecemeal fashion in an attempt to retain audience interest...Forever Evil may be a letdown, but it is a sincere and worthwhile attempt, given the resources at hand."
