In this sermon, Aaron Ernst emphasizes the importance of preaching the word of God and staying true to sound doctrine. He warns against the temptation to seek out teachers who cater to personal desires rather than teaching the truth. Ernst also discusses the characteristics of a true prophet, highlighting the importance of producing good fruit and leading people to repentance. He cautions against relying on worldly philosophies and emphasizes the need to recognize false prophets. The sermon is based on 2 Timothy 4:2 and Jeremiah 23:21.