Everyone believes in the same thing,

each person simply sees a different side of the picture.

Do we not all believe in the same supernatural force? The one that always was, who brought us into Being, who brought forth a prophet who is born, dies and is reborn through the power of a god/goddess/universe, and is the one who will carry us to a heavenly after-world so long as we loyally worship them?

God, Allah, Krishna, Ra, the Buddha, Ishvara, Zeus...

Is it not easy to see that we are all feuding over the same religion? The same religion: only different names.
Even if we're not speaking of religion, if you venture to different parts of the world and into different cultures, every human being has the same or similar routine and requires the same things in order to survive. If you're thirsty, it does not matter whether someone hands you "water," "agua," "вода," "l'eau," "νερό" or "wassar" - when you receive the glass and drink it, you will experience the exact same refreshing feeling no matter where you received it from and no matter what someone else called it.

If you transfer that thought process into religious terms, it does not matter whether someone seeks out "God," "Yahweh," "Ra," "Gaia," "the Universe," or "Allah." You must understand that on different parts of the planet, and growing up in distinctly different environments, cultures will perceive their supernatural forces in distinctly different ways.
For example, the ancient Nordic mythology believed in the Frost God, Ymir and the Ice Goddess, Audhumla. During the same era, the ancient Egyptian mythology spoke of the Sun God, Ra. Their stories of creation and births and battle are strikingly similar, however, the people of northern Europe knew of only ice and snow and chilling winters, while the people of northern Africa knew of only dry heat and the desert and harsh summers, which led them to correlate their supernatural force to their environment.

Is it so difficult a thing to believe that every single person on this planet is, in fact, right, and that every single one of us will enjoy a heavenly, or peaceful, afterlife for simply being?

We all have the same glass of water... How can you argue over who's glass is more refreshing, or more clear?

I am Lion; Hear me Roar.