Only in 1937, (WT November 1) did the society declare that JWs with an earthly hope could be described as Christian. The March 1, 1930, WT had said, "Since 'Christ' means the anointed of God, it is manifestly true that no one can properly be termed a Christian who is not in Christ and who has not received the anointing."
So, once again, the "truth" (the manifest truth, no less!) turned out to be wrong. Shucks, God must have just loved pulling their legs. ("Here's some new light via the Holy Spirit. Oh, just kidding!")
Don't know about the suggestion that only the anointed could be called JWs though.