From an article in The Briefing by Tony Payne
An ‘affection’ is not quite an ‘emotion’—at least not in the way we now use the word. For us, an emotion is a strong state of feeling that arises within us, sometimes suddenly and usually unbidden. An emotion is usually responsive; it is an outpouring—a bubbling over of some well of feeling within us—in response to some sort of stimuli.
An ‘affection’, however, is more closely linked to the inclination of our hearts—to what we love or hate. Positively, it is when we perceive something to be good, lovely, attractive, desirable, and so passionately long for it; or negatively, it is when we find something to be evil, ugly, deadly or repulsive, and so shrink or run from it.
Now the affections, as Edwards defines them, are not slight preferences either side of indifference, but “the more vigorous and sensible exercises of the inclination and will of the soul”. They are marked by sensations of love or hate, of rejoicing or loathing, of gratitude or bitterness, but the manifestation of these sensations is complicated and varies enormously, and is thus no real sign that a true and holy affection is at work. In fact, it is very possible for there to be false affections that mimic the genuine gracious affections that God works in our souls—affections that bring all affections into disrepute.
For Edwards, true Christianity is, in large measure, a matter of the affections. It is not enough to hear about God, or know of him, or even assent to the truth of the gospel. A true Christian undergoes a transformation of the heart by the Holy Spirit so that he no longer loves himself and the world and the devil, but loves God and his Christ. A Christian’s ‘vigorous and sensible inclination of the will’ is now towards God and his word, and away from the devil and his lies. This fundamental reorientation at the centre of our being—this change in what we love—refashions our entire lives. It reorients our relationships and priorities; it frees our minds to want to know more of God and to please him in everything; it humbles us and causes us to bewail and confess our sin; and it issues in Christian practice day by day.
And this change is effected by a divine, supernatural work of the Spirit of God, as he applies the word of God to our minds and hearts.