The article presents selected aspects of the impact of religion on how wars were waged in ancient Greece, taking into account the specificities of relations within the Greek world. The author points to the clear presence of war motifs in Greek mythology. He shows the influence of religion on different stages of war, from the decision to declare war through the actions being taken during it. He presents the legal consequences of violating peace rules during the games and the impact of holidays on the possibility of military action. He discusses the status of sacred sites and draws attention to restrictions on how to wage wars between members of the Delphic Amphictyony.