The question was put to me over lunch earlier this week and not for the first time. So I thought it worthwhile to post here a few reflections on the difference between the Reformed doctrine of common grace and the Wesleyan-Arminian doctrine of prevenient grace.
What is Common Grace?
The easiest way to clarify the difference between common and prevenient grace is to consider them both in relation to salvation. Common grace does not lead to salvation; prevenient grace does. In Reformed theology, common grace is not saving grace and is not regarded as part of soteriology (i.e., theology of salvation) or the order of salvation. Instead, according to Berkhof, it was developed in response to questions like these:
How can we explain the comparatively orderly life in the world, seeing that the whole world lies under the curse of sin? How is it that the earth yields precious fruit in rich abundance and does not simply bring forth thorns and thistles? How can we account for it that sinful man still "retains some knowledge of God, of natural things, and of the difference between good and evil, and shows some regard for virtue and for good outward behavior"?...How can the unregenerate still speak truth, do good to others, and lead outwardly virtuous lives? (Systematic Theology, 4.III.A.1.).
In short, how can sinful people who live in a fallen world do anything good or virtuous? The answer, from the perspective of Reformed theology, is common grace. Here's Berkhof again, common grace
curbs the destructive power of sin, maintains in a measure the moral order of the universe, thus making an orderly life possible, distributes in varying degrees gifts and talents among men, promotes the development of science and art, and showers untold blessings upon the children of men" (Systematic Theology, 4.III.A.4.)
So we might say that common grace is that which keeps the effects of sin in check to some degree and makes possible human culture and civilization.
It is essential, however, to understand that in Reformed thinking common grace is distinct from special (or particular and saving) grace. Common grace does not save people from condemnation; special grace necessarily effects the salvation of the elect to whom it is given. Berkhof points to several further distinctions between common and special grace Common grace is given indiscriminately to all people; special grace is limited to the number of the elect. Common grace never removes the guilt incurred by sin; special grace always does. Common grace doesn't renew human nature; special grace changes the inner person. Common grace is resistible; special grace never is.
What is Prevenient Grace?
While common grace is not considered saving grace, prevenient grace may very well lead to salvation, though not necessarily so. In Wesleyan-Arminian thinking, prevenient grace is simply the work of God in a person's life that precedes conversion and prepares that person to freely receive the gospel. In Reformed thinking, common grace is not part of the order of salvation; in Wesleyan-Arminian thinking, it is. At the risk of oversimplifying the order of salvation, prevenient grace leads to justifying grace, which leads to sanctifying grace and then glorifying grace. I'll hasten to add that since we Arminians see grace as resistible, it follows that prevenient grace need not always lead to justification and final salvation. Prevenient grace is not effectual. It does not effect salvation as the Reformed understand special grace to effect salvation. Rather, prevenient grace prepares the human heart to believe the gospel and be saved, but prevenient grace can be resisted. To summarize, if you can look back and see the work of God drawing you to Christ prior to your conversion, that is prevenient grace.
I should add that Wesley and Arminius had somewhat different views of the extent of prevenient grace. Wesley thought prevenient grace extended to all people in some degree in order to mitigate the effects of original sin. If I understand correctly, Arminius thought prevenient grace came specifically through the preaching of the gospel to free the hearts of those who hear to respond freely to the good news. Both saw prevenient grace as part of the order of salvation. Both understood it to be resistible. They differed on the scope and perhaps the means.
One more point of clarification is necessary. Prevenient grace is not substantially different from justifying or sanctifying grace. They emphasize different points in the same journey of salvation by grace through faith. The terms have to do with process and chronology; they are not different sorts of grace.
Two Different Graces?
I think people tend to confuse common grace and prevenient grace because both have the lost as their object. Otherwise, they have little else in common. They are fundamentally different concepts that address fundamentally different questions. Common grace answers the question of how fallen people can do anything that is not thoroughly wicked. Prevenient grace answers the question of how fallen people can be prepared to respond freely to the gospel.
In the end, Reformed theology seems to posit two substantially different forms of grace - one effective to salvation and one not. The problem, as I see it, is that this divorces grace from the work of Christ, which Berkhof acknowledges with regard to common grace. To be fair, he rejects the suggestion that there are two substantially different forms of grace by arguing that common grace is not attribute of God while special grace is. But if this is the case, why create confusion by calling it grace? Arminian theology successfully provides a coherent understanding of God's grace: there is only one grace, and it leads to and finds its fulfillment in Jesus and union with him.