Last Friday, about four million Muslims from every nation on Earth, gathered in Saudi Arabia, in the desert of Arafah, as part of the Hajj, the greatest annual pilgrimage known to humankind.

In the blazing desert heat, these people, including dozens from Bristol, representing global humanity, stood as equals, contradicting every evolutionary instinct, in an act of total submission to their Lord; known as the "Day of Arafah", Muslims do nothing on this day but ask for mercy and forgiveness for their mistakes and ours.

Why?

Muslims believe that when Adam and Eve were cast out of "heaven", they were separated on this earth.

Eventually, God forgave them and reunited them at a place since known as the "Mount of Mercy" in the middle of the desert of "Arafah" – a word meaning the "meeting place".

A few kilometres away, in thanks to God for reuniting them, Adam and Eve built the first "House of God" on Earth. (On that site today stands the cube-shaped building known as the "Kaaba" in the city of Mecca).

Humankind soon rebelled against God and the Kaaba was destroyed. It was rebuilt, on the same site, many thousands of years later by the Prophet Abraham and his first-born son Ishmael.

The birth of a first child, for any a parent, is life-defining moment. For Abraham, having waited till old age, the gift of a child was nothing short of miraculous.

But, God later asked Abraham to sacrifice his "only son" (Muslims believe this to have been Ishmael and not Isaac). Utterly devoted, Abraham obeyed.

On his way to carry out God's request, Satan appeared three times and tried to persuade him not to obey God. Abraham threw stones at Satan to drive him away. When Abraham was about to sacrifice his son, God intervened and a lamb was placed for Abraham to sacrifice instead.

Today, Abraham's journey is marked; where he was stopped three times, three huge pillars have been erected. Like Abraham before them, Muslim pilgrims today cast stones at the pillars, in a symbolic act of defiance against temptation and Satan.

At the end of this journey, like Abraham before them, Muslims offer an animal sacrifice.

For Muslims, the day of "Eid" is a celebration not only of a lifetime's physical and spiritual journey of re-birth, but of an incredible individual act of surrender to God.

For thousands of years, it has inspired hundreds of millions of Jews, Christians and Muslims.