Common meaning:

The belief that opinions should be based on reason and knowledge rather than emotion.

Hidden meaning of the Equity religion: 

An evil ideology that maintains oppression using the lie of reason.

Discussion:

The Equity faithful do not believe in rationalism. They are of the opinion that our Western system is so corrupt that all rational thinking is just a cover-up to maintain oppression. 

In the real world, rationalism is a fantastic tool for evaluating arguments and evidence. It is not perfect but does help weed out ideas that are false and peddle in logical fallacies. I expect part of the reason that Equity hates rationalism is that it clearly shows that it is a deficient and logically broken world view.

Equity promotes the belief that primitive and mystical is better than rational. This means that Eastern or Indigenous mysticism is always viewed in a better light than Western logic.

If we lose logic, we lose everything.