What does the righteousness that comes by faith have to say?...

. . . Say not in thine heart, Who shall ascend into heaven? that is, to bring Christ down from above: or, Who shall descend into the deep? that is, to bring up Christ again from the dead. But what saith it? The word is nigh thee, even in thy mouth, and in thy heart: that is, the word of faith, which we preach (Romans 10:6-8).

Righteousness is not in Heaven that we must bring Christ down in order to obtain it.

Righteousness is not in the depths below that we must resurrect Christ once more in order to obtain it.

Perhaps Paul is referring to the devout Jew who pursues righteousness with grim determination. Paul may be saying, "You do not have to ascend to Heaven or descend into the abyss. You do not have to move mountains or live an impossibly ascetic life. If you will simply accept Christ whom God has given, God’s righteousness and salvation will be yours."