If your Lord had willed, He would have forged the entire mankind into one creed, - but they will always be at loggerheads with each other -

11 : 119

Except those towards whom your Lord has been merciful! Mankind was intended for (disagreements) and the word of your Lord did come to pass when He said : 'Verily I shall fill hell with Jinn and mankind put together!'

(If Allah had willed, there would have been no factions among mankind, no fore-heads would have touched the floors of Tabernacles and Cathedrals; no hands would have tolled the bells of temples to invoke idols; no battles would have been waged between the Crusaders and the Defenders of Faith; no innocent lives would have been tortured to death in prison camps and no blood would have been spilled in the streets of Jerusalem at the start of a new millennium! But such is not the case. There is an implicit reminder for us in the verse that, when Allah banished Adam and Eve from Paradise, He did not say to them : 'dwell on earth bonded with the ties of mutual love and dedication!' He said : 'dwell on earth, each of you an enemy unto the other' and vowed to fill hell with mankind and Jinn who ignore His guidance and flout His Commandments, - promise we have helped fulfil by our misdeeds and mistaken loyalties).