John Calvin preaches about the ongoing struggle with sin in the life of a believer, emphasizing that depravity continues to produce sinful behaviors in us until we are freed from our earthly bodies. He highlights the promise of baptism for the submersion of sin, not for its complete eradication, but to prevent it from ruling over us. Calvin encourages believers to persevere in their fight against sin, acknowledging that progress is made as they see their sinful tendencies diminishing over time, leading to the ultimate victory over depravity at the end of their earthly lives.

Brethren, I count not myself to have apprehended: but this one thing I do, forgetting those things which are behind, and reaching forth unto those things which are before, —Philippians 3:13 Depravity never ceases in us, but is perpetually producing new fruits —those works of the flesh which we have already described, like the emission of flarne and sparks from a heated furnace, or like the streams of water from an unfailing spring. For lust never dies, nor is altogether extinguished in men, till by death they are delivered from the body of death, and entirely divested of themselves. Baptism, indeed promises us the submersion of our Pharaoh, and the mortification of sin; yet not so that it no longer exists, or gives us no further trouble; but only that it may never overcome us. For as long as we live immured in this prison of the body, the relics of sin will dwell in us; but if we hold fast by faith the promise which God has given us in baptism, they shall not domineer or reign over us. But let no man deceive himself, let no one flatter himself in his guilt, when he hears that sin always dwells in us. These things are not said in order that those who are already too prone to do evil may securely sleep in their sins, but only that those who are tempted by their corrupt inclinations may not faint and sink into despondency; but that they may rather reflect that they are yet in the way, and may consider themselves as having made some progress, when they experience their corruptions diminishing from day to day, till they shall attain the mark at which they are aiming, even the final destruction of their depravity, which will be accomplished at the close of this mortal life. In the meantime, let them not cease to fight manfully, to animate themselves to constant advances, and to press forward to complete victory. For it ought to give additional impulse to their exertions, to see that, after they have been striving so long, so much still remains for them to do. We conclude, therefore, that we are baptized into the mortification of the flesh, which commences in us at baptism, which we pursue from day to day, and which will be perfected when we pass out of this life to the Lord. —Institutes, IV, xv, xi