‘But the righteousness which is of faith says thus, “Do not say not in your heart, “Who will ascend into heaven?” (that is, to bring Christ down),” Or, “Who will descend into the abyss?” (that is, to bring Christ up from the dead).'
In contrast with the righteousness which is of the Law is the righteousness which is of faith. This presents us with a totally different picture. Whereas ‘observing the Law had required a constant, and unavailing struggle, the righteousness which is of faith was obtained solely by truly believing in the Messiah Who had died for them and risen again, and by genuinely confessing Him as LORD. It did not require great effort. It required submission and trust, and subsequently a whole change of attitude.
Paul exemplifies this in terms of Deuteronomy 30:11-14 LXX, although altering it from referring to God's commandment, to referring to the Messiah, who is, of course, God's Word (John 1:1-14; Hebrews 1:1-2; 1 John 1:1). It will be noted, however, that he does not in this case refer to his words as Scripture. There is no ‘the scripture says', or ‘it says', or ‘it is written'. It is ‘the righteousness of faith' that ‘speaks'. It is thus an explanation of the righteousness which is by faith. The wording then, although mainly taken from Scripture, is not necessarily being cited as Scriptural evidence. He is rather using what Moses says about God's commands as being something readily available, and applying it to the Messiah as Someone Who is readily available.
Just as it was with God's commands to Israel so was it with the Messiah. We do not have to find some means of accessing Heaven in order to bring the Messiah down, for He has been sent by God and is already present among us. We do not have to descend into the depths of the nether world (the word ‘abyss' could refer either to the depths of the nether world or to the depths of the sea) in order to bring the Messiah up from the dead, for He is already risen. No huge effort or mysticism is required, for the Messiah is not far away but near at hand.
In Amos 9:2 the idea of accessing Heaven or descending to the nether world was that of a task of great difficulty resulting from sheer desperation, something attempted in order to escape the hand of God. Something that the Psalmist knew was foolish to attempt, for they would find God there (Psalms 139:8). So Moses and Paul are thinking of a task of great difficulty, possibly even of desperation, as men seek God's truth. But Paul's point is that in the case of finding the Messiah it was unnecessary. He had come among us to reveal Himself to us. We may also see here that the Messiah was sent down from Heaven, and raised up from the nether world, in order that men and women may be able to access Him. That was why He was available. God had already done the difficult work for us.
On the other hand, if we bear in mind that Jesus as the Messiah was seen as ‘God's Word to man' (John 1:1-18), and as the One ‘through Whom God had spoken' (Hebrews 1:2), we can see why Paul could associate Him in his mind with ‘God's commandment', seeing Him as God's final commandment to men. In support of this is the reference to ‘the word' which is ‘near you, in your mouth and in your heart' (Romans 10:8). However, it may be that Paul was deliberately contrasting ‘the commandment' with the Messiah in order to emphasise by the substitution the contrast between works on the one hand and faith in the Messiah on the other. Either way the emphasis is on the fact that the Messiah is near at hand for all who would call upon Him.