So, what are the energies? Crudely speaking, they are the "activites" of God. Because God's essence is wholly other, outside of the realm of space and time, incomprehensible, we cannot come into direct contact with it. And yet God is a God who intervenes in his creation and enters into relationship with his creatures. It is the energies of God that we come into contact with. God's glory and love and goodness are all energies. According to Mike Horton:
God's energies are radiations of divine glory, but are no more the divine essence than rays are the sun itself. God's uncreated glory emanates, but the essence does not. ...[The energies are] God-in-Action... They are not God's essence, but a certain quality of God's self-revelation and saving love.
(Covenant And Salvation, 268.)
But we must also keep in mind that the energies are not ontologically separate from God's essence, nor are they parts or pieces of God. They are God.
This may seem a bit confusing, and I have not even begun to do the topic justice. This is merely an introductory post that, I hope, will show that such a distinction is desperately needed in Western Protestantism today. All that is important at this point is that idea that there is a distinction between God as He is in Himself (His essence) and God as He manifests Himself to His creation (His energies).
Now then, three reasons Evangelicals need to start thinking about this distinction:
1) Pantheism (or Panentheism)
There has long been a tendancy in the West toward a kind of Pantheism. Medieval mysticism and its quest for the Beatific Vision was an extreme form of this. If God is absolutely simple and "only" an essence, how do we come into contact with Him without in a sense become a part of Him? What does the Apostle Peter mean when he says that we will "partake" of the divine nature? Do we partake directly of God as He is in Himself? At the very least, this seems to imply some sort of Panentheism, which is the belief that God is contianed within and permeates all of the natural world, as if He were the "world soul." By positing the doctrine of the energies of God, we can explain how it is that we come into direct contact with God and even partake of Him without falling into this dangerous tendency of Western theology.
This is not as dangerous of a problem for Protestants today, but it is always a potential. If God is, as traditional Christian theology has always maintained, unchanging and impassible, not affected by his creation (as He says in Samuel, He is not a man that he should repent), one could easily come to the conclusion that God is like the great Stoic philosopher in the sky. After all, impassible could mean "cold" and "unfeeling." Perhaps God is just an impersonal being from which all reality flows, a being who doesn't care about us or love us (certainly not enough to save us from our sin). Again, the E-E distinction saves us from such extremes. God in His essence is simple, unchanging and impassible. But his energies are manifold. Through His energies He comes into contact and enters into relationships with his creatures, and in an analogous way He feels with them, responds to their pleas, etc.
3) Open Theism
I saved the best for last! Of the three reasons I've given, this one is obviously the biggest potential danger for contemporary Protestantism. After considering Stoicism, it should be easy to see how the E-E distinction will help here, since Open Theism is simply the opposite problem. Open Theists want a God who can feel our pain, react to our cries for help, and genuinely respond to our prayers. Ignoring for the moment that the incarnation of Christ solves many of these problems (Hebrews specifically addresses how Christ can empathize with our struggles with sin, for example), the E-E distinction does as well. God's essence can remain unchanging while His energies remain manifold. His essence is simple while His activities in creation are varied.
So, are you interested yet? At any rate, I hope you can see how potentially important this distinction can be for the problems facing modern Protestantism. As I said, I will continue to explore this theme in greater detail over the next year. This is only the tip of the iceberg. If I've managed to whet your appetite, you can hear more on the E-E distinction in Mike Horton's systematic theology lectures (click here), specifically the most recent lectures on the incommunicable attributes of God. For a slightly more detailed introduction to the topic and its relation to the early Reformers' theology, check out the last section of Dr. Horton's book Covenant And Salvation (click here to buy the book online).