“The Javanese are a different race than us; they live in a different region; they stand on a wholly different level of development; they are created differently in their inner life; they have a wholly different past behind them; and they have grown up in wholly different ideas. To expect of them that they should find the fitting expression of their faith in our Confession and in our Catechism is therefore absurd.
“Now this is not something special for the Javanese , but stems from a general rule . The men are not all alike among whom the Church occurs. They differ according to origin, race, country, region, history, construction, mood and soul, and they do not always remain the same , but undergo various stages of development. Now the Gospel will not objectively remain outside their reach, but subjectively be appropriated by them, and the fruit thereof will come to confession and expression, the result may not be the same for all nations and times. The objective truth remains the same, but the matter in appropriation, application and confession must be different , as the color of the light varies according to the glass in which it is collected. He who has traveled and came into contact with Christians in different parts of the world of distinct races , countries and traditions can not be blind for the sober fact of this reality. It is evident to him. He observes it everywhere.”
Abraham Kuyper
‘Common Grace’ III.XXXII
People groups vary and are different. Different people groups worshiping in different churches is not wicked.