 The voice once again speaks to Isaac 's mother , stating that Isaac must be cut off from all that is evil in the world . Once again , his mother obliges , and locks Isaac inside his room . Once more , the voice speaks to Isaac 's mother . It states she has done well , but it still questions her devotion , and tells her to sacrifice her son . She obliges , grabbing a butcher 's knife from the kitchen and walking to Isaac 's room . Isaac , watching through a sizable crack in his door , starts to panic . He finds a trapdoor hidden under his rug and jumps in , just before his mother opens his bedroom door . Isaac then puts the paper he was drawing onto his wall , which becomes the title screen . 
