Please check out the article on the Painful Truth that delves further into the past racist teachings in the Church of God.
You can also listen to the complete sermon by Herbert Armstrong here: Interracial Marriage
The Painful Truth has this:
The Plain Truth magazine was trumpeting these teachings to hundreds of thousand...maybe millions of readers right during the 1960s Civil Rights Era. Herbert insisted he wasn't "taking sides" in the Race Question that was the greatest problem of the d...his magazine wouldn't be promoting the demands of the Negro, nor would it be endorsing the approach of the segregationists of the Deep South. It was, he insisted, just telling the "Plain Truth" about what God thinks of it all, about what the Bible says about it all, and about what the Bible predicts for the future. The reality, of course, was that Armstrong did, indeed, "take the side" of the white anti-integration southerners. Often using some of the same arguments, the same "scripture quotations" that showed up on their protest signs. "God hates race-mixing." "God is the author of segregation."-–Myth America by Pam Dewey
These quotes below and many more are on the Painful Truth site. Far too many in the COG today continue to claim the church was never racist, but the track record proves otherwise.