You will be connected to a benevolent higher being, with personality, tenets, gender, and appearance, up to you- as such things are easy enough to humor you with.
They will select you as their champion and leader, entrusting you with the task of spreading their religion throughout the world.
As their champion, your mind will enter into the realm of the deity every time you fall asleep or request to be there while awake. They need your presence to act in the mortal world, conveying messages and energies through you.
The more followers they gain through worship, the stronger their influence. With enough people devoted to their cause, they can perform small miracles to protect and aid those loyal to their religion. The worship of an entire town will be enough to ward off an endbringer, while 90% of the population worshiping them could even take down an entity like Scion.