Calvin emphasizes that suffering is never a sign of God’s wrath towards us, much less a sign that we are not elect. Trials are the workshop of a Father, not the threats of a Judge. The arrow that looks as if it were targeting our heart is actually aimed at the sin that clings to us, so that we may be loosened from its grip. “Sometimes even when God delivers us from calamities, it is at the last moment, so that we can only cast ourselves upon him—and what an experience of growth this produces!” In fact, Calvin says, “Properly speaking, God is not angry with his elect, whose diseases he cures by afflictions as it were by medicines.” Christ has propitiated God’s wrath against us, so any trials that God sends our way are entirely for our good and should not be seen as an act of retribution for our sins.
We may never know how the particular trial served as God’s strong medicine. Indeed, we may never know whether the suffering was sent directly by God, but it is enough to know that he works even pain and evil together for our good and his glory. God would never allow a wound that he couldn’t heal. Furthermore, as Calvin notes, “The Son of God doth suffer not only with us, but also in us,” bearing us up and provoking within us by his Spirit the cry “Abba, Father,” even in our misery.
Calvin On the Christian Life by Mike Horton
This topic is also expanded in the question and answer session in a conference titled “Transforming Grace” which you can listen to here.