I'm sitting here drinking "filtered" water. The filter is an admission that the water provided by man is not pure. The filter is meant to remove any impurities from the water, purifying it.
The Word of God refers to itself as water - and it certainly starts out pure, but when it's given to us to drink by men without the Holy Spirit, it becomes mixed with man's spirit, or sometimes demonic spirits, and it's full of man's wisdom and it becomes full of impurities.
We must allow the Holy Spirit to "filter" the Word taught to us by men not anointed by Him to teach, so that the "impurities" - the false doctrines, are removed, that only that which the Holy Spirit teaches remains. His teaching is water our souls should drink in deeply. Without the Holy Spirit we cannot "rightly divide the Word" and we end up "wrongly dividing (understanding) the Word".
The first thing Pastor's seek to do is learn to teach God's Word. They go to Bible college for this reason (among others). Ephesians 4:11 shows us Pastor and Teacher are separate ministries yet Pastors believe they are called to teach. Some are, most aren't. James 3:1 - Revised version says - "Be not many teachers, my brethren, knowing that we shall receive heavier judgment". Indeed - denominations full of teachers, with no Apostles or Prophets, are a fulfillment of 2 Timothy 4:3&4. Exalting the teaching ministry over all others is a clear sign of the end times