It is the means by which God unites all of humanity in order to reveal his glory.
That He might make known the riches of His glory on the vessels of mercy, which He had prepared beforehand for glory. (Romans 9:23) "NKJV"
Without mercy, no one can comprehend God in all his glory. For God is not restricted to a particular religion, some religions, or religion.
Humanity was once alienated from God: even those that are now identifying with religion were not the people of God until God came and called them his people. The Jews, who were the first set of human beings to be called the people of God, were, like the rest of humanity, aliens to God.
Abraham was not the friend of God before God called him out of Babylon and made him his friend. There was no record of Abraham doing anything in Babylon that made God to separate him out of the midst of the Babylonians.
It is not of him who wills, nor of him who runs, but of God who shows mercy. (Romans 9:16) "NKJV"
After creating the Jews, God went out to call a new set of people who were the Christians. The Christians were called Gentiles in order to differentiate them from the Jews; although the term Gentiles implied all non-Jewish people.
Like the Jews, God called the Christians (the Gentiles) to himself even though the Christians didn't do anything to deserve it.
That Gentiles, who did not pursue righteousness, have attained to righteousness, even the righteousness of faith.(Romans 9:30) "NKJV"
Like he created the Jews and the Christians, God also created the Muslims, the Hindus, the Buddhists, the Taoists, the Philosophers, the Scientists, etc. All these other groups, like the Jews and the Christians, didn't do anything to deserve it.
The history of the world is the story of God restoring mankind back to the humanity he created in the beginning before he sent Adam out of the Garden of Eden. He created different groups in separate places, and after completing his work of creation, he reconciled the different groups into one humanity.
The reconciliation is the summary of every thing God created; the summary is the short work.
Summary = Short Work
God is no longer interested in what people did wrong, but in what they did right. He has decided to unite the world to himself through what humans did right.
The things the unbelievers did right constitute righteousness if they now believe in Jesus, and confess it with their mouths.
Short work: summary of the good things humans did in the history of the earth.
The good things humans did on earth constitute the radiance and the brilliance and the splendour of the cosmos.