Podo, a couple of Scriptures which show Spiritual understanding and knowledge gradually being revealed by Spirit, rather than exclusively by explicit statements of Scripture, are:
" "And you have an anointing from the holy one, all of you have knowledge... And as for you, the anointing you received from him remains in you, and you do not need anyone to be teaching you, but, as the anointing from him is teaching you about all things, and is true and is no lie, and just as it has taught you, remain in union with him." - 1 John 2:20, 27.
What is there possibly to learn by Spirit if it's all explicit in Scripture? If there was something deeply mysterious to be revealed about the nature of God, then it's reasonable that it would be revealed in a Spiritual manner, rather than in a primarily intellectual manner, through the written word. It's reasonable that the written word would merely contain the suitable indications to support what the Spirit directly revealed and clarified. This would easily be missed by those to whom it was not revealed by Spirit, and who were relying wholly on the written word and their power of reason.
As the Scripture above shows, Christians were to remain "in union with him" in accord with what the spirit revealed to them personally.