What can be said of someone who does not have the Spirit of Christ dwelling in him?...

He does not belong to Christ.

All the people of the world can be separated into two groups: those who have the Spirit of Christ dwelling in them and those who do not have the Spirit of Christ dwelling in them.

People who have the Spirit of Christ dwelling in them are Christians, regardless of their doctrinal beliefs. Those who do not have the Spirit of Christ dwelling in them are not Christians, regardless of their doctrinal beliefs.

In the last days, as the wheat and the tares come to maturity side by side, the division between Christians and non-Christians will become increasingly clear. When the Lord returns, those who are abiding in Christ will rise to meet the Lord in the air. Then the true Church will be one in Christ in God.