The Bible certainly does teach that the Scripture and the preaching of them are insufficient, in themselves, for understanding and faith.
John 3:19,20 (VW)
19 And this is the judgment, that the Light has come into the world, and men loved darkness rather than the Light, for their deeds were evil.
20 For everyone practicing evil hates the Light and does not come to the Light, lest his deeds should be reproved.
Now contrast this with the person whom God has made born again.
John 3:21 (VW) But the one doing the truth comes to the Light, that his deeds may be clearly seen, that they have been worked in God.