How simple it is to be righteous, how simple to enter the dwelling of the Father: everything is written in Ps 14! Only for some reason the previous psalm declares: "They have all turned aside; together they have become corrupt. There is none who does good, not even one." And Jesus, after giving the very simple "golden rule of ethics" (Matt 7:12), immediately adds that the way is narrow and few find it.
Apparently this simplicity is deceptive: these words are "simple" only when spoken by God, for whom righteousness is a natural state. But if these words are taken up, passed on, and received with faith, then salvation becomes possible and righteousness attainable.