Theophylact of Ohrid, on Heb 12:23

“And to the church of the firstborn, who are written in the heavens, and to God the judge of all, and to the spirits of the just made perfect,”

“Instead of fear, joy, which is what is signified by the word "celebrating." For where there is a celebration, there is joy. And so, this celebration takes place among the angels. He calls the firstborn those believers who are dedicated to God, sanctified, whose names are in the book of life, just as the Lord said to His disciples: "your names are written in heaven" (Lk. 10:20). And since God is the Father of all, all people are His sons; but the firstborn among them are those who have believed and are especially worthy of adoption. Or all believers in general are called sons; but the firstborn are those who have pleased God and who, for their word and their life, were deemed worthy to be messengers of God. Here he also frightens them. For He is the Judge of all, not of the Jews only, but of all believers. Therefore, fear this. He shows along with this also their advantage over those of the Old Testament, that those could not endure even the words alone and did not dare to approach even the mountain — but you have approached the Judge Himself, that is, Christ. "For the Father judges no one, but has given all judgment to the Son" (John 5:22). That is, to souls that have proven glorious and perfect before God, evidently by virtue of faith, as he clearly showed: and you will be united with them, if you imitate them.”

Imported from an open dataset — not yet checked against the printed edition.