Well, the answer is simple: “Life is the principle of self-activity.” So say the philosophers.
I think that answer is actually pretty brilliant, short and over-simplified as it is. I like basic principles; I like simple concepts on which you can build. This one is good, I think. It’s very important to understand the idea of life, because it seems to be fundamental to Christian doctrine. We talk about Eternal Life and it is mentioned often in Scripture, for example the famous John 3:16. We should know what we’re talking about.
I’ve concluded that the word ‘eternal’ does not mean ‘goes on forever.’ Rather, it is a characteristic unique to God and refers to how He lives outside of time. Eternal means to be unconstrained by time. Time is a creature, created by God and so not imposed upon Him. Eternal Life means the life of God. Yet, Scripture says that we can have Eternal Life, the life of God. How is this possible? Do we share in God’s nature?
Yes, we do. This is a most remarkable idea. Some of my Christian friends have been very incredulous when I say this is Catholic doctrine, yet I stand by it. For example, St. Peter says:
"His divine power has granted to us all things that pertain to life and godliness, through the knowledge of him who called us to his own glory and excellence, by which he has granted to us his precious and very great promises, so that through them you may become partakers of the divine nature, having escaped from the corruption that is in the world because of sinful desire." (2 Pet 1:3-4)
And those texts that speak of our eternal life: well, by the fact that only God is eternal and not us, then I believe they refer to God sharing His life with us (and not just us living forever – for the damned also live forever).
That this is Catholic doctrine, and not just my opinion, is clear from many meaningful texts of the Teaching Church over the ages. But the modern CCC (Catechism of the Catholic Church) comments on this clearly for us:
“The Word became flesh to make us “partakers of the divine nature” (2 Pet 1:4): “For this is why the Word became man, and the Son of God became the Son of man: so that man, by entering into communion with the Word and thus receiving divine sonship, might become a son of God.” (St. Irenaeus, Adv. Hares. 3, 19, 1:PG 7/1, 939) “For the Son of God became man so that we might become God.” (St. Athanasius, De inc., 54, 3:PG 25, 192B) “The only-begotten Son of god, wanting to make us sharers in his divinity, assumed our nature, so that he, made man, might make men gods.” (St. Thomas Aquinas, Opusc. 57: 1-4) (CCC 460)
The meaning here, as clarified by millennia of commentary and teaching, is that God shares His nature with us through a process of communion. I will post on this process later; for now, I only want to talk about the fact of this sharing of His nature.
This takes us back to the idea of Life. Per the above definition, a thing is alive if it has self-activity – i.e., it can act on its own. This is the difference between a rock and a lion: a rock cannot move by itself; it can only be moved by another. The lion can, however, act quite extensively on its own.
But, you may say, the lion really is just a complex flesh machine, acting not on its own, but only when external stimuli set the molecules of its brain in motion to run a particular algorithm. This brings us to the next idea: the degree of life. A lion has a degree of life – of self activation – that is greater than that of, say, a plant, but less than that of a human. A human can abstractly think; we can understand being and goodness and things that other animals cannot do (notice I said other – more on that another time). I can block out external stimuli and still I act. Yet, it’s still not complete self activity. I need food and air, etc. Only One lives Who alone acts completely on His own – that is God. He lives without need of anything else. He is pure existence; we say His nature is His existence, His acts are His very being.
It is this nature, to live without need of anything else, that He shares with us. This is Eternal Life. It is also the key to ultimate happiness, but more on that later. When we enter into communion with God, we receive the Gift of that Life. And as the knowledgeable Christian knows, the Greek word for gift is charis, translated in our English bibles as “grace.” The grace of God is the sharing of His Life, of His nature, with us. This is the idea of Christian life.
Other religions have approached this idea, differing mainly in method. They focus on practices that can lead to union with deity. Christianity differs in that it is not the practices that lead to communion, but rather it is God Himself who does the leading. Christian practices exist to enable us to recognize God’s call to grace; beyond that, we are passive. Quite frankly, many of these practices are teaching tools, symbolic in nature.
There is another difference though, which is a nuance: We believe God shares His nature with us and we become a composite creature, half human, half divine. Other religions tend to focus on identity rather than nature; union with the deity results in our joining identities rather than our natures. This is one of the problems I had when engaging in Eastern religions. I did not want to disappear as a drop of water disappears into the ocean, becoming the ocean; it smacks of annihilation. Even within Christianity there has been historical confusion between nature and identity (or person). The Monothelite heresy was perhaps caught in this confusion.
But notice that the idea of God sharing His Life with us does not, at face value, include any notion of an afterlife. We know that God will share His Life with us after we shed our bodies and go to heaven; yet that is not the only way. The sharing is here and now. We have the empirical knowledge of saints who have experienced the full power of this sharing in this world. I admit to experiencing the joy of God’s grace now and then, but it’s in infant form, stifled by my own roadblocks. I struggle to tear down the roadblocks. The saints have torn down the roadblocks and enjoyed full-on grace, their lives profoundly transformed and their joy complete. This is what I want.