The correct answer to this open question is the following.
Ancient Egypt was a mystical and religious nation. The life of ancient Egypt depended on religion and their relationship with their many deities.
RA was the supreme God. It was the Sun God, and every Egyptian pharaoh was thought to be its representative on Earth. That is why the pharaoh was honored and worshiped.
Every Egyptian pharaoh built monuments, temples, and impressive buildings to tell its deeds on the battlefield and to show the next generation it's accomplishments.
Egyptians had many Gods as was the case of Osiris, Isis, Horus, Seth, Hathor Anubis, among many others.
The concept of the afterlife was very important for Egyptians. In the case of the pharaoh, that is why he was mummified after his death, trying to preserve his body during his trip into the afterlife. The pharaoh ordered to bury him with all his richness and belongings he could need in the afterlife.
