Which was an important cause of the decline of the Roman Empire?

The Major Causes for the Fall of the Roman Empire Antagonism between the Senate and the Emperor Decline in Morals Political Corruption and the Praetorian Guard Fast expansion of the Empire Constant Wars and Heavy Military Spending Barbarian Knowledge of Roman Military Tactics Failing Economy Unemployment of the Working Classes (The Plebs) The 'Mob' and the cost of the 'Games' Decline in Ethics and Values Slave Labor Natural Disasters Christianity Barbarian Invasion The major causes for the Fall of the Roman Empire