"Now I want to remind you..." - We constantly need reminders that increase our fear of God. How often I go through the day with no thoughts of God, with only thoughts of self and my own goals and my own plans and my own wants. I need to be reminded that God is watching and that he is the one and only judge.

"...although you once fully knew it..." - It seems as though Jude's readership had done more than forgotten. They had also lost their confidence that God judges sin. They were living as if God may not really end up judging sin, at least not their sin.

"that Jesus, who saved a people out of the land of Egypt" - Jesus is the source of salvation. He called a group of people, to be his own, out of captivity and into freedom. He was going to bless them with their own land, their own government. Most significantly, he was going to be their own God.

"afterward destroyed those who did not believe." - the very one who saved also destroyed. There is one God and judge, and he saves and destroys. What is the difference between those saved and those destoryed? Not education, not race, not ethnicity. Faith is the differentiator. Believe and be saved.

Jude 1:5