Paul served as Timothy’s mentor. In fact, Paul referred to Timothy as his “son in the faith” (1 Timothy 1:2). As Timothy’s mentor, Paul gave Timothy truths with the intent that he would pass along those teachings to other believers. Though there are certainly variations of what should be taught, Paul laid out two foundational categories when he mentioned “words of faith and of good doctrine” (1 Timothy 4:6). Though specifics are given in the epistles of First and Second Timothy and Titus, every teaching should reflect the categories set forth by the apostle Paul. Even practical teaching ought to be based upon the words of God, as some teachings are good (2 Thessalonians 2:15), and some are bad (Matthew 15:9). Every teacher should teach with hopes of eventually learning from his students when they too become the teachers.
The Bible says that “out of the abundance of the heart the mouth speaketh” (Matthew 12:34). This means that the words proceeding out of our mouths originate in our hearts. When we speak bitter words, it is because there is bitterness within our hearts. David likened bitter words to arrows that pierce the flesh (Psalm 64:3). Our words ought to be “seasoned with salt” (Colossians 4:6); instead, we often allow our words to pierce through others. We tear people down rather than building them up. Why is this? Because we have a root of bitterness growing inside that finds its way from our hearts into and out of our mouths. Those who demean others generally do so because they are bitter. Attempts to justify this behaviour are fruitless because the Lord knows the root of the problem stems from our heart.