You’re absolutely right about rage, but in many cases restraint without anger is apathy. At the very least, it’s not true that anger is always the opposite of love, as you seem to posit here. Anger might arise when a person feels passion for injustice, and passion for injustice is a form of love—so long as we acknowledge (as you do) that those who commit injustice likely do so out of ignorance.
Sometimes love is anger plus empathy.
I’m thinking of the poem “Goodbye to Tolerance” by Denise Levertov. Here are the first stanzas:
Genial poets, pink-faced
earnest wits —
you have given the world
some choice morsels,
gobbets of language presented
as one presents T-bone steak
and Cherries Jubilee.
I don’t care
if I never taste your fine food again,
neutral fellows, seers of every side.
Tolerance, what crimes
are committed in your name.
And you, good women, bakers of nicest bread,
blood donors. Your crumbs
choke me, I would not want
a drop of your blood in me, it is pumped
by weak hearts, perfect pulses that never
to nightmare reality.
It is my brothers, my sisters,
whose blood spurts out and stops
because you choose to believe it is not your business.