The Course boils down to what is very simple:
"3533. There IS a choice which you have power to make,
when you have seen the real alternatives.
Until that point is reached you HAVE no choice,
and you can but decide how you would choose
the better to deceive yourself again.
This course attempts to teach no more than that
the power of decision cannot lie
in choosing different forms of what is still
the SAME illusion and the SAME mistake.
All choices in the world depend on this; -
You choose between your brother and yourself,
and you will gain as much as he will lose,
and what you lose is what is given him.
How utterly opposed to truth is this,
when what the lesson's purpose is to teach
that what your brother loses YOU have lost,
and what he gains is what is given YOU."
(T-31.IV.8)