We are now in the fourth and final section of Mere Christianity, the section entitled “Beyond Personality”. This section is all about what a God who is beyond personality looks like, and how we as humans can enter into the life of a God who is beyond personality. Lewis starts off by laying the groundwork for his conception of the Trinity with the distinction between “making” and “begetting”, with the key ideas that what man begets is man while what God begets is God, and that man is made by God but not begotten by God.
Lewis then goes on to illustrate how three persons could make up one God by using the example of dimensions; in one dimensional space all we know is lines, in two dimensional space lines combine to form figures, and in three dimensional space figures combine to form solids. In the same way, in the human “dimension” all we know is individual persons, while in the divine “dimension” three persons combine to form one God. Lewis then goes on to lay out how this understanding of three persons and one God fits with all that we know of how God operates in our lives, both on an individual level and at the level of the whole Church.
In this chapter Lewis digs deeper into the distinction between man and God as it relates to begetting. When one man (or woman) begets another, the one who begets always comes before the one who is begotten; that is, there is a stretch of time when the one who begets exists but not the one who is begotten. But when God the Father begets God the Son, both are in existence for all of eternity. There was never a point in time when God the Father existed but God the Son did not.
For those of us who live in this universe of space and time, that can be very difficult to wrap our minds around. Lewis uses the illustration of two books resting on a table, one on top of the other. Imagine that those books were sitting there on that table for all of eternity. Now the bottom book causes the top book to be in the position that it is in, and to stay in that position without falling down onto the table. But the bottom book was not there before the top book; both books were there for all of eternity. Thus the bottom book causes the position of the top book without preceding it; in the same way God the Father causes the existence of God the Son without preceding Him.
Another illustration: Imagine the two books resting on the table as in the previous illustration. Now imagine yourself holding that image in your head for all of eternity. Your act of imagining causes the image of the two books on the table to appear in your head. But the act of imagining does not precede the image; the image appears immediately, as soon as you imagine it. So if you have been holding this image in your head for all of eternity, then the act of imagining causes the image but does not precede it. Just as the Father’s act of begetting the Son causes the Son to come into existence, but the Father does not precede the Son, that is, there is no point in time when the Father exists and the Son does not.
Another way to think about this is to think of the Son as streaming out from the Father, as heat from a fire, light from a lamp, or a mental image from a mind. But in all of these images there is one difficulty: it makes you think that the Father and the Son are two things instead of two persons. All of the biblical language that we have describes the Father and the Son as persons; there must be a reason for this.
That is always what happens when you go away from the words of the Bible. It is quite right to go away from them for a moment in order to make some special point clear. But you must always go back. Naturally God knows how to describe Himself much better than we know how to describe Him. He knows that Father and Son is more like the relation between the First and Second Persons than anything else we can think of. Much the most important thing to know is that it is a relation of love. The Father delights in His Son; the Son looks up to His Father.
This leads us into Lewis’s next point: that “God is love”, as the Christians always like to say, implies that God must consist of at least two persons. This is because love is something which one person feels for another; thus if God was made up of only one person, the statement “God is love” would have made no sense prior to the creation of the world, and thus there would have been a time when God was not love, as there would have been no one and nothing for him to love.
This is, in Lewis’s opinion, the most crucial difference between Christianity and other religions. Other religions treat God as some static thing out there somewhere, but Christianity sees God as a dynamic, pulsating activity, the energy of love expressed between the Father and Son for all of eternity. And this energy, this “spirit”, if you will, is in fact the Holy Spirit, the third person of the Trinity. We see this at work in any group of people: whenever a couple, a group of friends or colleagues or coworkers, a fraternity or sorority, a church youth group, or any other organization gets together, they always have a sort of “spirit” about them, an identity together which is greater than that of the individuals who make up the group. This “spirit” is not something that anyone can see, but it causes the members of the group to do and say things when together that they would not do when apart. This influence, of course, can be good or bad.
But when the Father and the Son are together, their “spirit” is so strong that it actually produces another person–the third person of the Trinity, the Holy Spirit. It may be hard to wrap your mind around that, but that is part of the difference between how things work in the human “dimension” and how things work in the divine “dimension”. In the human dimension, when groups of people are together it does not produce anything except perhaps certain changes in the behavior of the people in the groups. But in the divine dimension, when the Father and Son are together it produces the Holy Spirit, the third person of the Trinity.
Heavy stuff, isn’t it? So what does it matter? It matters more than anything else in the world. Because if we are to attain the happiness that God created us for, we must enter into the life that is happening between the Father, the Son, and the Holy Spirit. Lewis likens the process by which this happens to a sort of infection, a “good infection” if you will, thus the title of this chapter.
Good things as well as bad, you know, are caught by a kind of infection. If you want to get warm you must stand near the fire: if you want to be wet you must get into the water. If you want joy, power, peace, eternal life, you must get close to, or even into, the thing that has them. They are not a sort of prize which God could, if He chose, just hand out to anyone. They are a great fountain of energy and beauty spurting up at the very centre of reality. If you are close to it, the spray will wet you: if you are not, you will remain dry. Once a man is united to God, how could he not live forever? Once a man is separated from God, what can he do but wither and die?
So how does one enter into this three-person life that is shared by the members of the Trinity?
Return to what Lewis said at the beginning of this section about making and begetting. We are made by God, not begotten by Him. We do not have Zoe, the special kind of life that God possesses. All we have is Bios, the natural life which eventually winds down and runs out, without fail. But the whole offer of Christianity is that if we let Christ have His way in us, we can come to share in the life of Christ, that life which was begotten, not made.
Christ is the Son of God. If we share in this kind of life we also shall be sons of God. We shall love the Father as He does and the Holy Ghost will arise in us. He came to this world and became a man in order to spread to other men the kind of life He has–by what I call “good infection.” Every Christian is to become a little Christ. The whole purpose of becoming a Christian is simply nothing else.