Those responsible for spiritual leadership must take care to know and teach the truth as they contend for the faith.
Today’s reading: Hosea 1-4; Jude 1
6 My people are destroyed for lack of knowledge;
because you have rejected knowledge,
I reject you from being a priest to me.
And since you have forgotten the law of your God,
I also will forget your children. Hosea 4:6
3 Beloved, although I was very eager to write to you about our common salvation, I found it necessary to write appealing to you to contend for the faith that was once for all delivered to the saints. 4 For certain people have crept in unnoticed who long ago were designated for this condemnation, ungodly people, who pervert the grace of our God into sensuality and deny our only Master and Lord, Jesus Christ. Jude 1:3-4
In both readings today, we see God indicting those who have forsaken the truth and misled those who looked to them for guidance.
Hosea, like other prophets, had a message of warning for Israel and Judah. He was also called to demonstrate God’s wrath against His people by taking a prostitute for his wife, showing the mercy and grace of God toward sinful, unworthy people. God told them they were destroyed for lack of knowledge. The nation had not been taught God’s law faithfully. The priests had facilitated national sin.
In a similar way, believers in Jude’s day were called to contend for the faith, that is, the doctrine given by God through the Apostles and Prophets, which was under attack by false and wicked teachers. These were deceitful and treacherous. They misused God’s grace as an excuse for sensuality. They denied the Lord Jesus Christ. Among other vices, they relied on their dreams. They got their own truth by direct revelation, a practice Paul also condemned (Colossians 2:18). 
Truth matters. It matters what we believe, and, if we are in the position of teachers, it matters to all whom we influence for good or bad. Be sure you know the truth of God’s word and that those you learn from contend for the faith and are not relying on their own dreams.
 The Reformation Study Bible, Sanford, FL, Reformation Trust, 2015, p. 2292. See note on verse 8