From the Genevan Doctor’s commentary on Romans 7–as a quick disclaimer, he was better at thinking than writing too sympathetically:
He now comes to a more particular case, that of a man already regenerated… But though the will of a faithful man is led to good by the Spirit of God, yet in him the corruption of nature appears conspicuously; for it obstinately resists and leads to what is contrary. Hence the case of a regenerated man is the most suitable; for by this you may know how much is the contrariety between our nature and the righteousness of the law…
The godly, on the other hand, in whom the regeneration of God is begun, are so divided, that with the chief desire of the heart they aspire to God, seek celestial righteousness, hate sin, and yet they are drawn down to the earth by the relics of their flesh: and thus, while pulled in two ways, they fight against their own nature, and nature fights against them; and they condemn their sins, not only as being constrained by the judgment of reason, but because they really in their hearts abominate them, and on their account loathe themselves. This is the Christian conflict between the flesh and the spirit of which Paul speaks in Galatians 5:17.
It has therefore been justly said, that the carnal man runs headlong into sin with the approbation and consent of the whole soul; but that a division then immediately begins for the first time, when he is called by the Lord and renewed by the Spirit. For regeneration only begins in this life; the relics of the flesh which remain, always follow their own corrupt propensities, and thus carry on a contest against the Spirit.
Regeneration, for Calvin, is strongly identified with remorse (the original meaning of our English “repentance”), and his self-loathing as the sign of a Christian veers even further from self-conscious virtue development and risks the danger of despair even more closely than some of Luther’s theology. For him, a high view of the Holy Spirit, especially an implicit idea of the Spirit’s ability to work deconstructively, to be present in the failures and compunctions and insurmountable limitations in willpower which we dread, which form us still.
The narrative of constant, visible spiritual progress is a non-starter – even according to the Reformer often (mis)credited with that idea. We don’t look at our behavior to see if we’re Christians; we look at our knowledge of ongoing sins. The Christian, for Calvin, will not feign obsequities, but actually, descriptively think that others are better (Phil 2:3), even (especially!) in ethical or spiritual stuff. Because the only way we truly learn low anthropology, and need for forgiveness, is firsthand; we read it in ourselves. The Reformation points of unity are the theology of the Cross, honesty about who we are, and a consequently high view of God’s grace specifically for sinners.