Step 4 of church discipline is the removal of the person from the church. When the church does this to a man, what is the church saying about his destiny?
Matthew 18:17 says, "If he refuses to listen to them, tell it to the church. And if he refuses to listen even to the church, let him be to you as a Gentile and a tax collector." (ESV)
On the positive side, if he repents, you have gained a brother. You may judge him a believer.
On the negative side, if he refuses, then you should consider him as a gentile. This isn't a strong declaration of unbelief. Jesus did not say, "You have lost your brother."
1 Corinthians 5:5,12-13 says, "You are to deliver this man to Satan for the destruction of the flesh, so that his spirit may be saved in the day of the Lord.
... For what have I to do with judging outsiders? Is it not those inside the church whom you are to judge? God judges those outside." (ESV)
Again, on the positive side, we judge those who are within the church. We declare them to be believers.
But on the negative side, we do not judge those who are outside. We leave that to God. And we hope that even Satan's attacks will cause him to repent.