The human ideas on which communism operates are false and evil. Our scriptural faith is that evil will NOT triumph. Where then is the "danger" of communism ?
The real danger is that Christians would be misled from scriptural faith to operate on false and evil human ideas. And a Christian who puts his/her faith in communism is not operating in the Spirit and the mind of Christ.
A Christian who puts his/her faith in capitalism, democracy, "conservatism," militarism, political partisanship, anti-communism, patriotism, or any other false and evil human idea from the secular realm has likewise ceased to operate in the Spirit and the mind of Christ.
Vastly more Christians are misled by those deceptions than by communism. Which false and evil human ideas, then, are a greater danger: those we reject, or those we take into our hearts and minds ?