John Calvin Commentary Romans 5:3

"And not only so, but we also rejoice in our tribulations: knowing that tribulation worketh stedfastness;" — Romans 5:3 (ASV)

Not only so, etc. Lest anyone scoffingly object that Christians, with all their glorying, are still strangely harassed and distressed in this life (a condition far from happy), he meets this objection and declares that not only are the godly prevented by these calamities from being blessed, but also that their glorying is thereby promoted. To prove this, he takes his argument from the effects, adopts a remarkable progression, and finally concludes that all the sorrows we endure contribute to our salvation and ultimate good.

When he says that the saints glory in tribulations, he is not to be understood as if they did not dread or avoid adversities, or were not distressed by their bitterness when they occurred (for there is no patience when there is no feeling of bitterness). Rather, since in their grief and sorrow they are not without great consolation—because they consider that whatever they bear is given to them for good by the hand of a most loving Father—they are rightly said to glory. For whenever salvation is promoted, there is no lack of reason for glorying.

We are taught here, then, what the purpose of our tribulations is, if indeed we are to prove ourselves to be the children of God. They should accustom us to patience. If they do not achieve this purpose, the work of the Lord is made void and ineffective through our corruption. For how else does he prove that adversities do not hinder the glorying of the faithful, except by showing that through their patience in enduring them, they experience God's help, which nourishes and confirms their hope? Therefore, those who do not learn patience certainly do not make good progress.

Nor is it an objection that Scripture records some complaints full of despondency made by the saints. For the Lord sometimes so depresses and constrains His people for a time that they can hardly breathe and can hardly remember any source of consolation; but in a moment He brings to life those whom He had nearly sunk in the darkness of death. So, what Paul says is always accomplished in them—

“We are in every way oppressed, but not made anxious; we are in danger, but we are not in despair; we suffer persecution, but we are not forsaken; we are cast down but we are not destroyed.”
(2 Corinthians 4:8)

Tribulation produces (efficiat) patience, etc. This is not the natural effect of tribulation. For we see that a large portion of humankind are thereby provoked to murmur against God, and even to curse His name. But when that inward meekness, infused by the Spirit of God, and the consolation, conveyed by the same Spirit, replace our stubbornness, then tribulations become the means of producing patience—indeed, those tribulations that in the obstinate can produce nothing but indignation and noisy discontent.