What economic issues are identified as causes for decline

Gibbons said that the fall of the roman empire was because of the decrease of its roman empire and the introduction to Christianity. 
Muller said that economic decline was because of the growth of the Latifundia, which left the little farms ruined, the abundance of slaves kept the wages low during this time. 
The Roman government had high taxes, causing a economic issue of declination because they needed to pay for their government the to maintain their military. 
So, the economic issues identified as causes for decline are the loss of the Roman faith or patriotism, the money put into the military/government, the decline of businesses,and the increase in poverty.