One primary way that God works in the lives of Christians to make them grow in godliness:
“By assuring the soul of his love, and shedding it abroad in the heart, and by working spiritual joy in the heart, does God also purge his people. And to work all these is in God’s power immediately and solely. “I am crucified with Christ,” (Gal. 2:20). And how? By believing that “Christ gave himself for me, and loved me.” This deadens a man to the world, and makes a man crucify that which Christ was crucified for; and this makes a man hate sin, the more he loves Christ, or apprehends his love.”
“The more joy a man has in Christ, the more deadened he must needs be to the world; the one eats up the other: for the ground of all sin is but the love of pleasure. Now if I find [pleasure] in God and Christ, it deadens me for seeking it in the world… when the sweetness of sin, the relish of it, is spoiled by the taste of a greater [sweetness], it must needs die and abate… none but a contrary pleasure will kill the sin and the pleasure in it.” Thomas Goodwin, The Trial of a Christian’s Growth, in Works 3:480.
There are many ways that God leads his people to decrease in sin and increase in sanctification. This is a primary way: by giving the heart an increasing pleasure in and affection for Christ. And that new affection is not just a pleasure in righteousness over the pleasure of sin; it is more basically and powerfully a pleasure in Christ and his love for us. We grow by trading “the sweetness of sin” and “the relish of it” for the sweetness of Jesus and a relish in him. And we get this by “apprehending his love.”
Grasping the love of God for us in Christ is not just the ‘first step’ as a Christian; it is the staircase. It goes further on and higher up than we yet know. If this ever feels old and tired to us, we are likely becoming less holy, not more, and this regardless of how holy we feel and appear to be. We don’t grow by trading sins for others, but by trading pleasure in sin for pleasure in Him.