Peace with God: Calvin's Commentary on Romans 5:1

When any one strives to seek tranquility of conscience by works, (which is the case with profane and ignorant men,) he labors for it in vain; for either his heart is asleep through his disregard or forgetfulness of God’s judgment, or else it is full of trembling and dread, until it reposes on Christ, who is alone our peace.  --John Calvin

1. Being then justified, etc. The Apostle begins to illustrate by the effects, what he has hitherto said of the righteousness of faith: and hence the whole of this chapter is taken up with amplifications, which are no less calculated to explain than to confirm. He had said before, that faith is abolished, if righteousness is sought by works; and in this case perpetual inquietude would disturb miserable souls, as they can find nothing substantial in themselves: but he teaches us now, that they are rendered quiet and tranquil, when we have obtained righteousness by faith, we have peace with God; and this is the peculiar fruit of the righteousness of faith. When any one strives to seek tranquility of conscience by works, (which is the case with profane and ignorant men,) he labors for it in vain; for either his heart is asleep through his disregard or forgetfulness of God’s judgment, or else it is full of trembling and dread, until it reposes on Christ, who is alone our peace.

Then peace means tranquility of conscience, which arises from this, —that it feels itself to be reconciled to God. This the Pharisee has not, who swells with false confidence in his own works; nor the stupid sinner, who is not disquieted, because he is inebriated with the sweetness of vices: for though neither of these seems to have a manifest disquietude, as he is who is smitten with a consciousness of sin; yet as they do not really approach the tribunal of God, they have no reconciliation with him; for insensibility of conscience is, as it were, a sort of retreating from God. Peace with God is opposed to the dead security of the flesh, and for this reason, —because the first thing is, that every one should become awakened as to the account he must render of his life; and no one can stand boldly before God, but he who relies on a gratuitous reconciliation; for as long as he is God, all must otherwise tremble and be confounded. And this is the strongest of proofs, that our opponents do nothing but prate to no purpose, when they ascribe righteousness to works; for this conclusion of Paul is derived from this fact, —that miserable souls always tremble, except they repose on the grace of Christ.  (Romans 5:1).

--John Calvin,  Commentary on Romans