Some argue that the office of the Papacy is the Antichrist, not the particular men who hold the office. It is a silly argument. The man who holds the office of Pastor is pastor while he holds it. So, the man who holds the office of the Antichrist is the Antichrist while he holds the office.
Does that mean that Roman Catholics are not Christians? No. It means that the Pope is the Antichrist. Individual Catholics may well be Christians, just as individual Lutherans of the most orthodox denominations may not be Christian at all. It is not one's label that makes them a Christian.
Those who belong to anti-Christian religious bodies are clearly not Christians. Those who choose not to belong to any Christian church at all are clearly not Christians. Those who disavow Christ and the church are clearly not Christians. But those who profess a faith in Christ may be Christian, and may not be, depending on what they mean by believing, and who they think Christ is, and what they believe about Him and sin and forgiveness and such topics. Then again, some who profess faith are quite self-consciously hypocrites. They are not Christians. But whether they are or not is in the hands of God to judge, not mine or anyone else's.
The judgement that the Pope is the Antichrist is Scriptural and Confessional. Those same Scriptures and Confessions instruct us not to be judging one another but to leave judgment to God. We may assess theological statements as to being true and in accord with Scriptures or not, but we cannot judge the heart of another. We don't have the ability to do it correctly, and we do not have the authority from God, to whom the job of judging hearts belongs.
Sadly, this doctrine of the faith has become a wedge to damage the political campaign of a candidate, and still it is not being addressed or examined for its meaning or truth. Our nation and the world are the worse for both of these realities.