Concerning the appearance of manifest injustice in the world, if I may use the analogy of a garden: When the Gardener first puts a seed into the ground, the seed finds a snug and safe place that provides for all of its needs. It is happy there. As it grows and develops, however, it begins to find the conditions oppressive and unsafe. The burgeoning plant starts to reach for the sky, and if it is to survive, it must gain it; only then can its development continue as it should.
This world is a place of training and development, both for individual souls and all humanity. As a collective entity, we are sore-pressed under the groaning weight of centuries of accumulated soil. Some recognize that this is foreign to our maturity and fight against it, breaking toward the light; others long for the material wealth of the dirt and hold the plant back, even though it stunts our growth. The few are even ready to sacrifice the majority to hold on to what benefits them, and revel in the freedom of their evil.
This is manifest injustice and must be fought against. The dire necessity of this battle increases day by day. However, it is not an injustice of the Farmer. He does not pull up the plant during these tender stages of its development. He sends His Messengers to nourish us and educate us, giving us the strength and understanding necessary to complete the task. Now, to grow full and strong, the fledging tree of humankind must struggle to find the light. There is no other way; too much assistance would leave us weak and incapable.
Yet the Farmer here isn’t just a separate Entity who watches from above. That’s just a weakness in my analogy. In our case, the will of the Farmer is not just the planting: but the soil and the rain and the sun itself; it’s in the physical laws, the development of life, and the potential of the seed. Everything lives and moves by His will, even if in the moment there are battles that must be won by our hand.
When it comes to divine Justice, this is a Law that none can escape. It is part of the nature of reality itself, like gravity or thermodynamics. Thus He says, “God will provide for each out of His abundance.” (Qur’án). And as Bahá’u’lláh explains in the Tablet of the Rights of the People (https://bahai-library.com/brown_lawh_haqqu_nas), all accounts are made whole, all debts are paid. To excerpt from a provisional translation of that tablet:
“Were I to explain and remove the veil from the manifestations of the deeds, acts, and words that appear in limitless and manifold forms in the worlds of God, it is feared, on the one hand, that sanctified souls would forsake their bodies and ascend to the seats of the glory of the All-Merciful; and, on the other, that the wicked and perverse would perish out of fear for what they have committed during their futile lives.” — Bahá’u’lláh
We dwell in a world of darkness, seeking the light. This darkness can often appear as manifest injustice, and that we have been left to fend for ourselves with no helper. Yet the darkness begets keenness of vision. Untold pain and sorrow and unjust suffering are experienced here; but the spiritual world bestows only the joy. It is a fundamental leap in perspective, I know, but there is more at play than just what we see ahead.
“O My servants! Sorrow not if, in these days and on this earthly plane, things contrary to your wishes have been ordained and manifested by God, for days of blissful joy, of heavenly delight, are assuredly in store for you. Worlds, holy and spiritually glorious, will be unveiled to your eyes. You are destined by Him, in this world and hereafter, to partake of their benefits, to share in their joys, and to obtain a portion of their sustaining grace. To each and every one of them you will, no doubt, attain.” — Bahá’u’lláh