"But for good people to do evil things, that takes..."

religion...yes...

or...

government
a war
a chain of command
an order given and followed
a basically good person yielding to fear or pressure of some sort
a social custom
a misunderstanding
a body of law
false information
the desire for vengeance
a feud
a grudge
a vendetta
a need to "win" (an election or some other contest)
etc, etc, to infinity.

To say that only religion can cause good people to do bad things is ridiculous.

Any strongly held belief system can cause good people to do bad things. Nationalism, for example, is a belief system. It causes good people to do bad things. It has killed far more people than religion has in the last few hundred years. It has ravaged entire societies and destroyed entire cities with fleets of bombers.