All to Him I owe. Absolutely nothing is lacking in the work of God for the salvation of man. God's love and mercy is universal. No one is excluded. Men may be partial and prejudiced toward their fellowman.
Injustice occurs when some are unfairly rewarded while others are discriminated against.
This cannot happen before God. The Savior died for those who crucified him, for Adolf Hitler, and for you and me. No one was excluded. The infinite mercy of God neither ignores nor neglects any man. Consider the following parallels from God's physical laws of nature.