This is the really tough proposition in the world today.
Of course the line between Good and Evil runs through every human heart (Solzhenitsyn) - but it used to be possible to identify Good and Bad institutions in terms of their aims and the preponderance of their activities; and to support the basically-Good against the essentially-Evil.
Either we aren't very good at this now, or else things are more mixed up plus there is less good; there are fewer people who are even trying to live by the Good. It has become acceptable to attack and subvert the Good in pursuit of the 'Better'.
(i.e. What we have is inevitably imperfect; and this is used as a reason to attack what we have - even or especially those Good aspects of what we have - because to do otherwise would be, 'complacently', to accept evil.)
OK but what should we do?
My feeling is that each should seek to discern what is essentially evil, what is pursuing evil as its basic activity - and we should fight it, or if not fight then try not to support it, or if not able to withdraw support then at least cooperate minimally (slowly, inefficiently, ineffectively) with it.
(i.e. Pursue a transcendental and moral version of the Good Soldier Svejk strategy - while continually looking around for counter-Good to which support might be granted. This strategy can be combined with a greater humility - since it entails being regarded as a simpleton and fool).
Finding positive things to support is the most difficult, since it is (surely) better to do nothing than to aid that which has (like everything) good aspects but is essentially evil.
(This is pretty much what is meant by the Antichrist - that which masquerades under a guise of some Christ-like attributes - but which is essentially subversive of Christ: things like communism and political correctness, or anti-Christian Christian-heresies.)
The conclusion, as I see it, is that this is - ought to be - a period of mystical activity, of prayer and humility, and not much of direct action.
(This conclusion has many other reasons as well as this one: I feel sure that it is correct. Our activities should be directed at sanctity. When heart, head and body [roughly soul, intellect and instinct] are severed apparently without much chance of re-unification, then we need to enhance the heart; and not the head or the body. When the heart is re-built, then - but only then - can the head and body return.)