Why should anyone believe in 'God'? ...............................

Because it allows them to shed responsibility for their actions eg GOD'S WILL

It gives them power over the actions of others eg. DICTATING GOD'S WILL

It allows them to commit atrocities in his name and yet feel no guilt. eg RELIGIOUS WARS/ INTOLERENCE

It allows them to feel superior and special eg GOD'S CHOSEN PEOPLE

It allows a heirarchy to make control the masses by blackmailing them into behaving in a particular way. eg HEAVEN and HELL