John Calvin Commentary Hebrews 12:23

"to the general assembly and church of the firstborn who are enrolled in heaven, and to God the Judge of all, and to the spirits of just men made perfect," — Hebrews 12:23 (ASV)

The firstborn, etc. He does not call the children of God indiscriminately the firstborn, for Scripture calls many His children who are not of this number. But for the sake of honor, He adorns with this distinction the patriarchs and other renowned saints of the ancient Church. He adds, which are written in heaven, because God is said to have all the elect enrolled in His book or secret catalogue, as Ezekiel speaks.

The judge of all, etc. This seems to have been said to inspire fear, as though he had said that grace is offered to us in such a way that we still ought to consider that we are dealing with a Judge, to whom an account must be given if we presumptuously intrude into His sanctuary polluted and profane.

The spirits of just men, etc. He adds this to indicate that we are joined to holy souls, which have put off their bodies and left behind them all the filth of this world; and therefore he says that they are consecrated or made perfect, for they are no longer subject to the infirmities of the flesh, having laid aside the flesh itself. And therefore we can with certainty conclude that pious souls, separated from their bodies, still live with God, for otherwise we could not possibly be joined to them as companions.