Sri Ramakrishna:
"I have practised all religions - Hinduism, Islam, Christianity - and I have also followed the paths of the different Hindu sects.
I have found that it is the same God toward whom all are directing their steps, though along different paths. You must try all beliefs and traverse all the different ways once.
Wherever I look, I see men quarrelling in the name of religion - Hindus, Mohammedans, Brahmos, Vaishnavas, and the rest. But they never reflect that He who is called Krishna is also called Siva, and bears the name of the Primal Energy, Jesus, and Allah as well - the same Rama with a thousand names.
A lake has several Ghats. At one, the Hindus take water in pitchers and call it ’ Jal ’ ; at another the Mussalmans take water in leather bags and call it ’ pani '. At a third the Christians call it ’ water '. Can we imagine that it is not ’ Jal ’ , but only ’ pani ’ or ’ water '? How ridiculous!
The substance is One under different names, and everyone is seeking the same substance; only climate, temperament, and name create differences. Let each man follow his own path. If he sincerely and ardently wishes to know God, peace be unto him! He will surely realize Him."
•••
Ra:
“Were there no potentials for misunderstanding and, therefore, understanding, there would be no experience.”
•••
…and there’s the answer to “do not resist evil”, Oleksii 
(I needed some time out in the wild with this one).
Resisting the opposite polarity, resisting “anything’s” antithesis, is resisting existence (experience) itself. There is only ONE power, not two (good & evil)…and this is the “non-dual” realisation the sages speak of.
The two polarities belong to the ‘relative world’, not the ‘absolute world’. Anything whatsoever can only be recognised and known in the relative world, due to the simultaneous existence of its antithesis.
Have a conversation with someone who was born blind, and she will tell you she has no conception of darkness, because she has no conception to light. Everything in the relative realm implies its antithesis, light implies darkness, happiness implies sorrow, birth implies death (in the absolute realm there is no death).
A magnet has two poles (north & south), cut off the south pole and it immediately forms a new south pole - they go together.
Wish away (reject) anything that causes you displeasure, and you might as well wish away anything that causes you pleasure. No appreciation of beauty would be possible without its comparable opposite - ugliness.
All of the above has to do with “realisation” and “insight”, not action, as per the example of the fourth density battle you mentioned. How to act when faced with “evil”, there are wisdom lessons involved there… we have a saying in our culture “what you fight, you strengthen” and “what you resist, persist”. …don’t know if it’s of relevance in this conversation…
Ra did say it’s the most difficult work of fourth density, so I think it might be above our paygrade for now. 
Different densities, different lessons. We are heading to the density of love and understanding (4th), so we are learning love lessons, and opening the heart.
They (fourth density) are heading to the wisdom density (5th), so they are learning wisdom lessons.
I just think if Ra can’t even describe fourth density to us in terms of what ‘it is’, but rather what ‘it isn’t’, because it’s beyond our comprehension, then how much else is beyond our comprehension, especially something described as “most difficult”.
So I regretfully have to make myself scarce. Thanks everyone for an interesting exchange of ideas!