Below are portions of an article he wrote in 1993 (!). And there’s also a powerful story in this article.
"Racism is a sin precisely because it keeps us from obeying God’s command to love our neighbor, and because it has its roots in pride and arrogance. Christians who harbor racism in their attitudes or actions are not following their Lord at this point, for Christ came to bring reconciliation—reconciliation between us and God, and reconciliation between each other. He came to accept us as we are, whoever we are,
'from every tribe and language and people and nation' (Rev. 5:9).
"Tragically, too often in the past evangelical Christians have turned a blind eye to racism or have been willing to stand aside while others take the lead in racial reconciliation, saying it was not our responsibility. (I admit I share in that blame.) As a result, many efforts toward reconciliation in America have lacked a Christian foundation. Our consciences should be stirred to repentance by how far we have fallen short of what God asks us to be as his agents of reconciliation. Of all people, Christians should be the most active in reaching out to those of other races, instead of accepting the status quo of division and animosity.
"The issues that face us are complex and enormous, and simply wishing they would go away will not solve them. I do not pretend to know the full answer. But let those of us who claim the name of Christ report of our past failures and relying on the Holy Spirit, demonstrate to a weary and frightened world that Christ indeed 'has destroyed the barrier, the dividing wall of hostility...through the cross, by which he put to death their hostility' (Eph. 2:14-15)."