The Nature of Conversion, Then and Now
I am now convinced, that conversion under the old [covenant] was not only the same in general with what it is commonly under the new, but much more like it as to the particular way and manner, than I used to think.
Among the children of Israel, there was always without doubt two sorts of persons, wicked and godly, and there used to be as manifest a difference between these two as there is now. It appears that the wicked were the same as they are now: vain, profane, light, proud, scornful, hating the godly. The righteous, by the descriptions we have of them, were also the same: humble, meek and lowly, devout, full of fear, love and trust in God, just, righteous and charitable. And we can't question but that there were as frequent conversions from one to the other as there is now.
This turning is very often spoken of in the Old Testament, frequently urged and encouraged; and we have no reason to believe that what was said had no effect. And undoubtedly the first motives of their turning were a sense of the dangerousness of sin, and of the dreadfulness of God's anger; and [they] were convinced so much of their wickedness, that they trusted to nothing but the mere mercy of God, and then bitterly lamented and mourned for their sins. Wherever turning is urged, such a turning as this is urged; and what instances we have were of this kind. And thus it doubtless was, not only amongst the Israelites but also among the antediluvians, and from the beginning of the world.
—Jonathan Edwards, Miscellanies #39