Can multiculturalism work? What should our attitude as Christians be toward the same?
Multiculturalism is the belief that people from diverse cultures can peacefully co-exist without changing. It doesn't work because there is no effort at uniting the groups, only a pretense if unity by ignoring the differences. Actual attempts at unity are disparaged or even condemned as taking away from a group's heritage. The end result is that the groups are driven apart, all in the name of "unity."
The church is composed of diverse people. "Then to Him was given dominion and glory and a kingdom, that all peoples, nations, and languages should serve Him. His dominion is an everlasting dominion, which shall not pass away, and His kingdom the one which shall not be destroyed" (Daniel 7:14). However, it doesn't seek differences, but a coming together in unity. "I, therefore, the prisoner of the Lord, beseech you to walk worthy of the calling with which you were called, with all lowliness and gentleness, with longsuffering, bearing with one another in love, endeavoring to keep the unity of the Spirit in the bond of peace. There is one body and one Spirit, just as you were called in one hope of your calling; one Lord, one faith, one baptism; one God and Father of all, who is above all, and through all, and in you all" (Ephesians 4:1-6). It is done by recognizing that there is only one standard under which we live. Paul didn't ask people to get along in their differences but to have unity knowing that is a single standard for us to accept. "Now I plead with you, brethren, by the name of our Lord Jesus Christ, that you all speak the same thing, and that there be no divisions among you, but that you be perfectly joined together in the same mind and in the same judgment" (I Corinthians 1:10).
There are frequent attempts at ecumenical movements. These fail because there is not single recognized standard of authority to which everyone must conform. Instead there is a desire to find the minimum to which everyone can agree and then declare that it is good enough. The problem is this always excludes someone because no one agrees on everything. So the group gets watered down and eventually fractures because they have nothing in common anyway.
Unity comes when people put effort into coming together around a single standard. Refusing to adapt or change toward that single standard produces division and conflict.