Corporations and the ultra rich are pretty new arrivals in the picture and I am willing to give them the benefit of the doubt.
This is fairly naive and also misses the fact that corporations have been around for a very long time too and don't have a great moral track record either. The Dutch East India Company at its peak dwarfed any modern corporation in terms of wealth and power[1] and was incredibly exploitative and corrupt. The British East India Company caused Opium addiction in China and kickstarted the colonisation of India. Industrial capitalists created (and still create) inhumane working conditions for their workers. If you count the whole sum of human misery created by the economic demands of the slave trade it becomes harder to even confidently assert that governments or religions have caused more evil.
This is not necessarily to say that corporations have caused more evil than governments or politics, but they do have a long track record of evil too and shouldn't be given "the benefit of the doubt" any more than any other organisation with a large amount of power.
[1] http://www.visualcapitalist.com/most-valuable-companies-all-...