I think you mistook what Rhamiel said. He said saints are those who are in heaven, and you took that to mean that all the saints are in heaven because they have been designated as saints on earth; ie by man.
In fact it is the other way round. They become saints by virtue of their faithful lives, which have now ended, and they have entered eternity by the Grace of God.
What Rhamiel actually meant, I think, is that anyone who has entered eternity with God is a saint, as indeed is true. This is not just those who the Church has been able to recognise as saints, but includes many tens of thousands of others known only to God, and may or may not include Martin Luther; it is not for us to judge either way those who are not designated as saints by the Church.
The Church does not create saints; it recongises what God has himself accomplished, and it does not do this lightly.