2 Timothy 2:15 Do your best to present yourself to God as one approved, a worker who has no need to be ashamed, rightly handling the word of truth.
If we have the Holy Spirit to lead us in all truth, why do we need pastors and teachers?
Ephesians 4:10-12 English Standard Version
10 He who descended is the one who also ascended far above all the heavens, that he might fill all things. 11 And he gave the apostles, the prophets, the evangelists, the shepherds and teachers, 12 to equip the saints for the work of ministry, for building up the body of Christ,
Equipping the saints is a process that takes time. First we must see to the issues associated with calling the lost and seeing to their training in the word of truth.
There is a transitional period where the renewal of the mind unlearns worldly ways and aligns understanding and belief measured against the whole counsel of God.
Isaiah 28:17 And I will make justice the line, and righteousness the plumb line;
Think of the plumb line as the vertical application of truth related to the base, that is square and true, not skewed. It must not be moved by every wind of doctrine.
Ephesians 4:14 so that we may no longer be children, tossed to and fro by the waves and carried about by every wind of doctrine, by human cunning, by craftiness in deceitful schemes.
Amos 7:7 This is what he showed me: behold, the Lord was standing beside a wall built with a plumb line, with a plumb line in his hand.
What is built upon the Cornerstone must meet His exacting standards.
Teachers are to keep measurements of their teaching to the rightness of the plumb line.
Titus 1:9 He must hold firm to the trustworthy word as taught, so that he may be able to give instruction in sound doctrine and also to rebuke those who contradict it.