No evidence exists that any god has walked the face of Eberron, those religions that worship gods give faith to the aspect of a god and believe they exist without any form of proof.

The Blood of Vol

• Everyone has a spark of divinity. Find that power within.
• Death is the end, Dolurrh is oblivion, and if the gods exist, they are cruel. Stand with those you care for; all we have is this life and each other.

The Seekers of the Divinity Within (as the faithful of the Blood of Vol call themselves) believe that the spark of the divine exists within everyone.
Because of the faiths connection to Undead many outsiders consider this religion evil.
The Blood of Vol is outlawed in Karrnath.

The Sovereign Host

• The Sovereigns are with us at all times. Onatar stands at every forge, and Dol Dorn is with you whenever blades are drawn.
• The Sovereigns shape the world. They offer us guidance and strength, but we must learn to listen.
• Honor every Sovereign in their place and time. If you hear one voice clearly, embrace their path.
• The hand of the Sovereigns can be seen in all things. What others take to be intuition or instinct, they see as the voice of the Sovereigns offering guidance. They don’t need absolute proof; the fact of a bountiful harvest is evidence of Arawai’s benevolence.

The host is a Pantheon of Nine gods and the primary religion of Khorvaire. Most people worship the Host as a whole but some few will give praise to one over the others.

The Host consists of:
Arawai, goddess of fertility
Aureon, god of law and knowledge
Balinor, god of beasts and the hunt
Boldrei, goddess of community and home
Doi Arrah, goddess of sunlight and honour
Doi Dorn, god of strength at arms
Kol Korran, god of trade and wealth
Olladra, goddess of good fortune
Onalar, god of craft

The Dark Six
While the Dark Six are a part of the religion of the The Sovereign Host, they are rarely worshipped but rather understood to exist.
Some cults do exists in Khorvaire especially amongst the Goblinoid tribes of Darguun.

The Six consists of:
The Devourer, god of nature’s wrath
The Fury, goddess ofwralh and madness
The Keeper, god of greed and death
The Mockery, god of violence and treachery
The Shadow, god of dark magic
The Traveler, deity of chaos and change

The Silver Flame

• The Silver Flame is force of light that holds fiends at bay. Those who seek to defend the innocent from evil can draw on the power of the Flame.
• Every mortal soul can find the light. Inspire and guide others to virtuous behavior; force is a last resort.
• Listen to the Voice of the Flame; beware the deceiving whispers of the Shadow in the Flame.

The Silver Flame is a powerful force said to exist everywhere in Eberron, though a manifestation of it is present in Thrane.
Worshippers dedicate themselves to living lives without evil, and the Church itself is dedicated to eradicating supernatural evil from Eberron.

Cults of the Dragon Below

• A paradise exists within the world, a vale bathed in the light of the Inner Sun. Earn your passage with the blood of worthy foes.
• Our existence is a chrysalis state, preparing us for transcendent immortality within the bowels of the gibbering mouther.
• The Lord of Eyes sees all secrets. Its gaze elevates the worthy and slays the unbeliever. Drive doubt from your heart, and you will see reality through new eyes.

Not any one religion, more a collective name for Demon worshippers or those that give praise to evil entities.