Let us read all of 1:6: “If we say that we have fellowship with Him and walk in the darkness, we lie and are not practicing the truth.” To lie is of Satan. He is the father of liars (John 8:44). His nature is a lie, and it brings in death and darkness. With darkness is falsehood, the opposite of the truth. The satanic darkness is versus the divine light, and the satanic lie is versus the divine truth. As the divine truth is the expression of the divine light, so the satanic lie is the expression of the satanic darkness. If we say that we have fellowship with God, who is light, and walk in the darkness, we lie, we are in the expression of the satanic darkness, and we do not practice the truth in the expression of the divine light. This verse inoculates against the heretical teaching of the Antinomians, who teach freedom from the obligation of the moral law and say that a person may live in sin and at the same time have fellowship with God.
If we would maintain the divine fellowship, we must not only walk in the divine light, but also practice the divine truth, which is versus the satanic lie. The Greek word rendered “practicing” in 1:6 is poieo. This verb denotes doing things habitually and continually by abiding in these things. Hence, it is used in verse 6 in the sense of practice. This word is also used in 2:17, 29; 3:4 (twice), 7, 8, 9, 10, 22; 5:2; Romans 1:32, and various other places.
To practice the truth is to live the truth habitually, not merely to do it occasionally. To practice the truth is to do it constantly, continuously, unceasingly. This can be compared to breathing, which is constant, continuous, habitual. While we are speaking, we are breathing. There is no need for us to make up our minds to breathe or to try to energize ourselves to breathe, for breathing is natural and habitual. Hence, breathing is a practice. In a similar way, when we abide in God as light and when we walk in the divine light, we spontaneously practice the truth habitually.
Suppose a certain believer is in darkness. Because he is in darkness, whatever he does, whatever he practices, is wrong. He may try to go in a certain direction, but that will be wrong. If he tries to go in another direction, that also will be wrong. But if this believer is in the light, he will automatically practice the truth. He will live, behave, and talk to others in a proper way. This is to practice the truth.
If we are in the light, we shall see the church as a reality. We shall also see the Body and the members of the Body as realities. We shall see that we are a particular member of the Body. But if we are in darkness, we may think that we are a great member of the Body, such as the shoulder, when actually we may be a small member, such as the little finger. This is another illustration of the fact that to be in darkness is to be in emptiness, vanity. But to walk according to what we see of the reality in the light is to practice the truth.
Often when we are in darkness we practice things that are nonsensical. For example, if a young person is in darkness, he may criticize an older brother in the Lord. This criticism is altogether nonsensical, for it is in darkness. This young person does not know what he is saying, and his criticism is vain and empty. He is not practicing the truth, because he does not see the truth.
It is when we are in the light that we see the truth. If we are in the light, whatever we do will be real. Not only shall we practice what is right and proper; we shall do what is real. This means that whatever we do is a reality. Habitually and automatically, we shall practice the truth, the reality. If we do this, we shall keep ourselves in the divine fellowship.