The Great Pyramid was a device built by Ra for spiritual initiations.

When you go into the tunnel in the subterranean chamber you experience your worst fears. Why do you think its closed off to tourists? Why do you think people have bitten by exotic snakes etc in this tunnel before?

This is the first initiation room, it weeds out those who are not true and ready for true enlightenment.

The "Queen's Chamber" and "King's Chamber" are also initiation rooms. In the Kings Chamber, the initiate is to lay inside the "sarcophagus" for approximately 3 days. (The "sarcophagus" was moved from its original position in the exact center of the pyramid so it won't work today although the tunnel in the subterranean chamber still works.)

Why do you think those Granite slabs above the King's Chamber are shaped that way? Why do you think the King's Chamber resonates at a certain frequency.

“If you want to find the secrets of the universe, think in terms of energy, frequency and vibration. ... Even if we do not add vibration in the form of sound, the vibrations are always there in the form of photon oscillations with the future unfolding with each new photon electron coupling or dipole moment." - Nikola Tesla