“As it is written, The just shall live by faith.” Christ is “our life.” Colossians 3:4. We are “saved by his life.” Romans 5:10. It is by faith that we receive Christ Jesus, for he dwells in our hearts by faith. Ephesians 3:17. Dwelling in our hearts, he is life, for out of the heart are the issues of life. Proverbs 4:23. Now the word comes, “As ye have therefore received Christ Jesus the Lord, so walk ye in him; rooted and built up in him, and established in the faith.” Colossians 2:6, 7. As we receive him by faith, and we walk in him as we have received him, we shall “walk by faith, and not by sight.”
This seemingly difficult expression, which has been the subject of so much controversy, is very simple when we allow the Scripture to explain itself. In the Gospel “the righteousness of God” is “revealed from faith to faith; as it is written, The just shall live by faith.” Note that “from faith to faith” is said to be parallel with “the just shall live by faith.” Just means righteous. The reader has noticed that some versions have “righteous” in 1 John 1:9 where the KJV has “just.” Both are the same. God’s life is righteousness; he desires that our lives shall be righteousness also, and therefore he offers to us his own life. This life becomes ours by faith. That is, just as we live naturally by breathing, so we are to live spiritually by faith, and our whole life is to be spiritual. Faith is the breath of life to the Christian. So just as we naturally live from breath to breath, we are to live spiritually from faith to faith. We can live but one breath at a time; so we can not live spiritually except by present faith. If we live a life of conscious dependence upon God, his righteousness will be ours, for we shall breathe it in continually. Faith gives us strength, for those who have exercised it “out of weakness were made strong.” Hebrews 11:34. So of those who accept the revelation of God's righteousness “from faith to faith,” it is said, “They go from strength to strength; every one of them in Zion appeareth before God.” Psalm 84:7
Let us not forget that it is from the very words of the Bible that one is to learn. All the real help that any teacher can be to any one in the study of the Bible is to show him how to fix his mind more clearly upon the exact words of the sacred text. Therefore, first of all, read the text over many times. Do not do this hastily, but carefully, paying particular attention to every statement. Do not waste one moment in speculating as to the possible meaning of the text. There is nothing worse than guessing the meaning of a text of Scripture, unless it is the acceptance of somebody else’s guess. Nobody can know any more of the Bible than the Bible itself tells; and the Bible is just as ready to tell its story to one person as to another.
Question the text closely. Probe it again and again, always in a reverent, prayerful spirit, to make it reveal itself. Do not be discouraged if you do not at once see all that there is in the text. Remember that it is the word of God, and that it is infinite in its depth, and that you can never exhaust it. When you come across a difficult statement, go back and consider it in connection with what precedes. Do not think that you can ever get at the full meaning of any text apart from its connection. By constant application to the words of the text, in order to be sure that you know exactly what it says, you will soon have them constantly in your mind; and it is then that you will begin to reap some of the rich fruits of Bible study; for at unexpected times new light will flash from them, and through them from other scriptures as you read.
"Waggoner on Romans" : by Ellet J. Waggoner : p. 1.27