Sodom's original line-up consisted of Tom Angelripper, Bloody Monster, Arius "Blasphemer", and Aggressor. The band was initiated by Tom as a desperate attempt to get out of having to work in coal mines in his home town of Gelsenkirchen. Though the band became a real working unit yet only when Chris Witchhunter (Christian Dudek, originally from Essen) had joined the band on drums (replacing Bloody Monster), having had already experience in writing music in some of his previous school-projects and thus coaching the remaining two members how to write proper songs (Arius had also been fired from the band).
Taking inspiration from bands such as Motörhead, Venom, Tank, Accept, Rainbow and AC/DC, the group continued as a three-piece in the Motörhead-fashion and released two demos which led to a record deal with Steamhammer. Aggressor left the band shortly before releasing the In the Sign of Evil EP (generally regarded as an important early black metal release), and was replaced by Grave Violator, who himself did not last long, and left following the recording of In the Sign of Evil. Michael "Destructor" Wulf was found as a replacement, after which the band went and recorded Obsessed by Cruelty, their full-length debut featuring music that was mostly in the vein of In The Sign of Evil. Wulf did not last in the band long, and later went and joined Kreator (he would not last long there either, and he died in 1993 after a tragic motorcycle accident).