Apostle Paul makes somewhat weird statements in this verses. “But the righteousness that is based on faith says, ‘Do not say …. ‘The word is near you in your mouth and in your heart’ (that is, the word of faith that we proclaim)” (ESV). Why does he say that? What is the specific point that he makes by that? What is the relation of the point to the context, the near and remote ones? In the passage around the verses (vv. 5-13), Paul teaches the faith system (the new covenant system) in contrast to the Mosaic system (the legal system; the old covenant system). The specific point that he makes here is the contrast between the two systems and the sufficiency of faith and the gospel for salvation. The point is the central principle of the new covenant system and it is explained apparently in every book in the NT and also it is taught in the OT too in various ways.
Paul begins the passage with what Moses did and commanded. He “wrote” about the righteousness. This reminds us of Deut. 31:24, which says, “Moses had finished writing this law in a book to the very end.” Among many things we can be reminded of by this statement, one thing that Paul is emphasizing in the context, is the fact that Moses “wrote” the law, which the text says of as “about righteousness.” What Moses wrote about righteousness refers to the Mosaic Law, as we generally refer to as the Pentateuch. Verse 6 summarizes what the Mosaic Law was for, which is expressed in terms of salvation in many OT verses (Lev. 18:5, Ezk. 20:11, 13, 21; cf. Gal. 3:12), for example, Deut. 6:25, which emphatically says that to do ‘all’ the commandments of God is the righteousness. The law is something that was written by someone and is independent of the person. the someone who wrote down the law in a book to the very end is Moses and he was with the people who were living with him.
However, the faith system is not the same with the legal system. It requires not a law but faith and the gospel; it suffices with the gospel and faith. First it does not need the written law, that gives people rules and statutes that they have to keep. Second, it means it does not need any ‘law,’ which is composed of codes written in “letters” like the Mosaic Law that requires certain actions and behaviors regardless of the circumstances and situations (cf. 2 Cor. 3:6). Third, the faith system needs to receive, instead of the law, the gospel—the stories of Jesus, how he was born, lived, and died, including his teachings, which relates what God wants from his people, that is, the will of God (cf. Heb. 10:7, 9). Therefore, what the new system requires of its followers is to receive the gospel and believe the one who is the origin of it, Jesus Christ the Son of God. For this reason Paul talks about the gospel and the significance of right reaction to it in the following passage, verses 14 through 21.
Verses 6-8 carries out these points. We do not need the Christ to be with us in body because the new system is by faith—faith does not need to see by sight the thing that one has faith in. Instead of the bodily presence of the Originator, like Moses’ among the Israelites, faith is necessary and sufficient. For this reason, the believer never says, ‘Let me see the Christ in my eyes then I will believe the gospel,’ which many nonbelievers use as their argument for their unbelief. Verses 6-7 point this out. Rather, the believer puts his heart and trust in the word, that is, the gospel that was proclaimed by the apostles and the New Testament books. They appreciate the word not only in their heart (faith) but also in their mouth (confession). The faith in and confession of the word represent the attitude of the believer to the gospel, in which righteousness of God is revealed. Because of their attitude, which is righteousness of God by faith, they are saved (vv. 9-11).
By all these points, Paul clarifies that the new system is the one by faith, which never needs ‘any’ law. Also he clarifies that the gospel is the origin of salvation (cf. 10:14-21). These facts are in the contrast with the old system which was by law and by works of the law. The principle—salvation is by faith and faith comes from listening to the gospel—is the central one and the foundation of the new covenant system. It is explained apparently in every book in the NT and also it is taught in the OT too in various ways. The book of Romans is one that focuses on it very directly. The books of Galatians and Colossians are very strong to explain the contrast between the old and the new system. Hebrews deals with this topic most exhaustively. In the Gospels, what Jesus teaches is about the failure of the old system and the need for the new and all about the new system—what it is and what it requires. These I listed are just a couple of examples we can easily agree on in the NT that they are teaching about it. For the time concern, I would not to list those in which the OT teaches it. But let me point out what the NT says that it was the thing that the OT people were supposed to get through the Scripture: Romans 3:30; 9:31-32; Heb. 4:2; Acts 7:51; and Matt. 9:13.
Romans 10:6-8 sounds somewhat weird because of the rhetorical questions. But the weirdness is coming from the lack of understanding of the passage. When one understands it, it is a great and powerful analogical expression of the points that Paul are making. As usual with the general purpose of adoption of rhetorical expressions, Paul is emphasizing his points. Why? Because it is so important that one has to dig deep enough to understand the true meaning behind the expressions. If one simply disregards some expressions that sound weird he will not learn anything from them. What if it is God’s will to hide significant things to such ones (cf. Matt. 13:10-17)? Also if one simply assumes he knows what they mean without proving his understanding through the scripture, he will fall into a pit of distortion of the Scripture. The sin is never to be little, especially if he spreads it among others. One has to understand this teaching before he teaches others, because it is the whole gist of the Bible to the Christians. In other words, the passage teaches nothing very different from the teaching of the whole NT; it teaches the new system for salvation, which is by faith, and the significance of the gospel.