The Holy Spirit is the teacher in all things, in this world their must also be biblical teachers that guide the people in the things of God.
New believers are babes in Christ because they are new to the faith so they will need milk, this means they need the spiritual foundational teachings of Christ.
1Therefore, rid yourselves of all malice and all deceit, hypocrisy, envy, and slander of every kind. 2Like newborn babies, crave pure spiritual milk, so that by it you may grow up in your salvation, 3now that you have tasted that the Lord is good. 1 Peter 2:1-3 NIV
Although they are not blind anymore because Jesus has opened their eyes to Him of that He is the Saviour of the world, they need a teacher in the world who has sound doctrine that fully correlates to the word of God.
13What you heard from me, keep as the pattern of sound teaching, with faith and love in Christ Jesus. 14Guard the good deposit that was entrusted to you—guard it with the help of the Holy Spirit who lives in us. 2 Timothy 1 13-14 NIV
Babes in Christ being new to the faith, if they then start to teach on spiritual things that are more advanced than what they have understanding of they can lead people astray because they themselves are still on milk.
13He replied, “Every plant that my heavenly Father has not planted will be pulled up by the roots. 14Leave them; they are blind guides. If the blind lead the blind, both will fall into a pit.” Matthew 15 13-14 NIV