What to take into account when adding a large planet that is close to your world?

This might sound confusing but basically in my world there are sort of two main celestial things around my Earth. There's the sun, but there's also a planet I added that's believed by the people to be the place where the Gods live. It's close to my Earth so it looks really really big in the sky. Because of this, I wanted to know how this would affect my Earth. It doesn't shine or anything like the sun, it's just there like a giant Jupiter and is always visible to the people. Is it possible to have a planet close to my Earth without having it orbit the Earth? Is it realistic to have it always apparent, regardless of day or night?