The "Necessary Inference"
It has long been recognized by Bible students that there are three ways in which God's will is made known through his word: (a) by direct command or precept; (b) by an approved example, and (c) by a necessary inference.
Concerning the first of these, the direct command or precept, there can be little room for doubt or questioning. The desire of God is expressed in positive, peremptory mandates. The necessity of faith in Christ, of repentance, and of baptism into his body all fall into this category. Likewise the observance of the Lord's Supper is enjoined with a solemn, imperious, and unmistakable "This do." The precepts concerning the moral life are definite, positive, and stated in such language as to permit of no misunderstanding. It might almost be said that every single duty of the Christian is enjoined upon him by some plain, succinct, and clear-cut command, usually stated in the imperative mood, from God's word.
There are, however, a few duties which we learn by "approved example." As a case in point, it might be difficult for us to understand on which day of the week God desires us to eat the Lord's Supper had He not given us an "approved example" (Acts 20:7) showing that it was the "first day of the week" upon which the early Christians (under the guidance of inspired men) met for the stated purpose: "to break bread." By this "approved example" we discern God's will, and faithful Christians in every age have carefully observed the Lord's Supper "upon the first day of the week." Others, less concerned about doing things "according to the pattern" have decided it is a matter of indifference, and have their "observance" on any day that may suit their fancy — most often on a Thursday.
But what do we mean by saying that we learn God's will "by necessary inference"? What is an inference, and what is a necessary inference? An easy example will clarify the point: "And it came to pass in those days that Jesus came from Nazareth of Galilee, and was baptized of John in the Jordan. And straightway coming up out of the water, he saw the heavens rent asunder, and the Spirit as a dove descending upon him." (Mark 1:9, 10.) Now, if there were not a single intimation anywhere else in all the Bible as to the "mode" or "action" of Jesus' baptism, and if we had no idea at all as to the meaning of the word "baptize," we would of necessity infer that Jesus had gone into the water before it was possible for him to "come up out of it." No other conclusion is possible. It is a necessary inference.
But consider the matter of sabbath keeping. If we start with the acceptance of Jesus' statement that the Holy Spirit would guide the apostles "into all the truth" (John 16:13), and go on to Paul's declaration that the inspired scripture is profitable "that the man of God may be complete, furnished completely unto every good work" (2 Tim. 3:17) and finally give full weight to Peter's words "that his divine power hath granted unto us allthings that pertain unto life and godliness" (2 Peter 1:3), we are compelled to believe that the Bible is a complete revelation of God's will for us. There is not one thing he wants us to believe, or do, which is not here set forth; there is no command, no desire on God's part for any act of obedience, which is not clearly set forth in the pages of His Word.
When we closely study the New Testament we find that every commandment of the Decalogue (the Ten Commandments) has been re-stated and repeated in the New Testament except the fourth — the command to keep the sabbath day. We, therefore, necessarily infer that the keeping of the sabbath holy is NOT a part of God's will for His children under the Christian age. If God's revelation to us were incomplete, and did NOT contain "all things that pertain unto life and godliness," we might suppose the sabbath to be included among the things about which God's will had not been made known. But such is not now possible; for His will, His complete will, is revealed. Hence, it resolves itself merely into a question of obedience or disobedience. God has shown His desire in the matter. Man will either respect it or he will not.
By precisely the same reasoning we see clearly that instrumental music has no place in Christian worship. Under the old covenant it was used freely. David wrote many of the Psalms for use with instrumental accompaniment. Whether he did it with God's sanction may be a moot question; but that he at least had God's toleration for his instrumental music is hardly to be denied. But when we come to the New Testament, and study the terms and manner of worship Christ ordained for his people, we cannot but be impressed by the singular absence of all mechanical music. Since the inspired volume gives to us "all things that pertain unto life and godliness," we necessarily infer that instrumental music is to have no place in the worship that Christians offer God. It is not just a "possible" inference, but a "necessary" one. We cannot account for the omission of instrumental music from the Lord's church on any other ground than a deliberate, purposeful, and significant removal of it by the Lord from the worship his people had been accustomed to render.
God's will is made known by direct precept, approved example, and necessary inference. We dare not ignore any of these three channels of learning.
— F. Y. T.