Major Gods are the primary gods that supply you with an Archaic Age Spell, and a certain boost based on what kind of major god you get/choose. Major Gods also determine what you get for which kind of minor gods you can worship as well; thus meaning which major god you have is extremely important.
Classical Minor
Heroic Minor
Mythic Minor
Greek
Zeus
Hermes/Athena
Apollo/Dionysus
Hera/Hephaestus
Poseidon
Hermes/Ares
Dionysus/Aphrodite
Hera/Artemis
Hades
Athena/Ares
Apollo/Aphrodite
Hephaestus/Artemis
Egiptyan[]
Ra
Bast/Ptah
Hathor/Sekhmet
Osiris/Horus
Isis
Anubis/Bast
Hathor/Nephthys
Osiris/Thoth
Set
Anubis/Ptah
Sekhmet/Nephthys
Horus/Thoth
Norse
Odin
Freyja/Heimdall
Njord/Skadi
Tyre/Baldyre
Thor
Forseti/Freyja
Bragi/Skadi
Tyre/Baldrye
Loki
Forseti/Heimdall
Njord/Bragi
Tyre/Hel
Atlantean[]
Oranos
Oceanus/Prometheus
Theia/Hyperion
Helios/Hecate
Gaia
Oceanus/Leto
Rheia/Theia
Atlas/Hecate
Kronos
Prometheus/Leto
Rheia/Hyperion
Helios/Atlas