Hi, Robert Sock!
This is an excellent passage for those Scirpturalists… the origin of the prophecy is prior to Jesus so if we adhere to the letter of the Law nothing else should be Written and there should be no need to Teach anyone about God.
But notice what the passage actually tells us:
“…and they shall be my people…”
This Spirit comes only to those who become God’s people:
**44 While Peter was still speaking the Holy Spirit came down on all the listeners. 45 Jewish believers who had accompanied Peter were all astonished that the gift of the Holy Spirit should be poured out on gentiles too, **(Acts 10:44-45)
Once a person learns about Jesus and God’s Salvific Plan there’s no need to teach them about that which they’ve learned. The Holy Spirit, that dwells in the Believers, helps us understand the fullness of Truth. Yet, Truth cannot be revealed (taught) over and over.
The New Testament Writings served to do both (introduce [Teach] and remind [expand on the Truth through definition and doctrine]):
**15 If you love me you will keep my commandments. 16 I shall ask the Father, and he will give you another Paraclete to be with you for ever, 17 the Spirit of truth whom the world can never accept since it neither sees nor knows him; but you know him, because he is with you, he is in you.
26 but the Paraclete, the Holy Spirit, whom the Father will send in my name, will teach you everything and remind you of all I have said to you.** (St. John 14:15-17, 26)
However, when the Spirit of truth comes he will lead you to the complete truth, since he will not be speaking of his own accord, but will say only what he has been told; and he will reveal to you the things to come. (St. John 16:13)
Maran atha!
Angel