True repentance rests on God's goodness

"Yet we must remember to exercise restraint, lest sorrow engulf us. For nothing more readily happens to fearful consciences than falling into despair. And also by this stratagem, whomever Satan sees overwhelmed by the fear of God he more and more submerges in that deep whirlpool of sorrow that they may never rise again. That fear cannot, indeed, be too great which ends in humility, and does not depart from the hope of pardon. Nevertheless, in accordance with the apostle's injunction the sinner ought always to beware lest, while he worries himself into dissatisfaction weighed down by excessive fear, he become faith. For in this way we flee from God, who calls us to himself through repentance.

"On this matter, Bernard's admonition is also useful: 'Sorrow for sins is necessary if it be not unremitting. I beg you to turn your steps back sometimes from troubled and anxious remembering of your ways, and to go forth to the tableland of serene remembrance of God's benefits. Let us mingle honey with wormwood that its wholesome bitterness may bring health when it is drunk tempered with sweetness. If you take thought upon yourselves in your humility, take thought likewise upon the Lord in his goodness" (Calvin, Institutes, 3.3.15).