I am afraid I don't understand how Plato is evil.
As I see it, reality exists whether we perceive it or not.
Off the top of my head, what prevents us from perceiving the truth can be:
1) our desire to avoid the truth because it is inconvenient
2) being misled by lies
3) not taking the trouble to find the truth because we are indifferent to it
4) going with the flow because we want to be mainstream and not wanting to incur disapproval by speaking an inconvenient truth
Plato's Ideal Forms are useful up to a point and helps us perceive God as an aggregation of every idea good and evil that we can think of.
The
concept and ideal form of beauty is one that everyone can agree with, because they think they will recognise it when they see it, though it is only in the eye of the beholder.
The ideal form of God is that He is omnipotent and perfectly moral even if we might argue about what being omnipotent, perfectly moral actually means and disagree about the morality of His laws.
The ideal form of God is even knowable to the atheist because he understands the concept of being omnipotent and being perfectly moral, even if the atheist denies God's actual existence.
Restoring Truth, Logic and Morality with Secular Koranism