John Calvin Commentary John 8:35

"And the bondservant abideth not in the house for ever: the son abideth for ever." — John 8:35 (ASV)

Now the slave remains not in the house always. He adds a comparison, taken from legal and civil principles, to the effect that a slave, though he may have power for a time, yet is not the heir of the house; from this he infers that there is no perfect and durable freedom except that which is obtained through the Son.

In this manner he accuses the Jews of vanity, because they hold only a mask instead of the reality; for, concerning their being Abraham’s offspring, they were nothing but a mask. They held a place in the Church of God, but it was a place like that which Ishmael, a slave, rising up against his freeborn brother, usurped for a short time, (Galatians 4:29). The conclusion is that all who boast of being Abraham’s children have nothing but an empty and deceitful pretense.