What he had said generally concerning the commandments he now applies again to the Sabbath, and not without reason. For, as we said yesterday, God not only wished by that day of rest to exact from the people what was due to him, but he rather commands it for another purpose, namely, that his Sabbaths should be sanctified. But the manner of keeping it holy was formerly explained, since mere rest was insufficient. God was not satisfied by the people's resting from their occupations, but the inward sanctification was always the chief end in view. And for this reason he also repeats again, that they may be a sign between me and you to show you that I Jehovah am your God. In this passage God bears witness, that if the Jews rightly observed their Sabbaths they should feel the effects of that favor which he wished to be represented thereby. For we said that the Sabbath was a sacrament of regeneration: now therefore he promises the efficacy of his Spirit, if they did not shut the door by their own impiety and contempt. Hence we see that sacraments are never destitute of the virtue of the Spirit unless when men render themselves unworthy of the grace offered them. When papists speak of the sacraments they say that they are efficacious, if we only remove the obstacle of mortal sin: they make no mention of faith. If a person is neither a thief, nor an adulterer, nor a homicide, they say that the sacraments produce their own effect: for example, if any one without a single particle of faith intrudes himself at the table of Christ, they say that he receives not only his body and blood, but the fruit of his death and resurrection, and only because he has not committed mortal sin; that is, cannot be convicted of theft or homicide. We see how they are steeped in blindness, according to God's just judgment. We must hold, therefore, that there is a mutual relation between faith and the sacraments, and hence, that the sacraments are effective through faith. Man's unworthiness does not detract anything from them, for they always retain their nature.
Baptism is the laver of regeneration, although the whole world should be incredulous (Titus 3:5
the Supper of Christ is the communication of his body and blood, (1 Corinthians 10:16,) although there were not a spark of faith in the world: but we do not perceive the grace which is offered to us; and although spiritual things always remain the same, yet we do not obtain their effect nor perceive their value, unless we cautious that our want of faith should not profane what God has consecrated our salvation.