9 • But when the archangel Michael,
contending with the devil,
was disputing about the body of Moses,
he did not presume to pronounce a blasphemous judgment,
but said, "The Lord rebuke you."
10 • But these people blaspheme all that they do not understand,
and they are destroyed by all
that they, like unreasoning animals, understand instinctively.
11 • Woe to them!
For they walked in the way of Cain
and abandoned themselves
for the sake of gain to Balaam's error
and perished in Korah's rebellion.
Moses had witnessed contention against him get to the pitch that after Korah's rebellion, which you can read all about in Numbers 16, Aaron had to run through the camp of Israel with a censer full of fire from the altar to 'head off' God's anger and prevent it from resulting in the deaths of all Israel. Now this happened the day after the ground had opened up and swallowed whole the followers of Korah with their families, their contention going down with them to the world of the dead, to Sheol. You would have thought that we would learn the lesson not to contend with God in this way but if, the very day after rebellion was swallowed up by the ground, the people could be complaining that the rebellion was the fault of Moses (and therefore of God) how can we expect that mankind will ever cease to shake his fist in God's face.
Certainly, Moses could see a history of such behaviour going right back to the beginning of time. At the time of Korah's rebellion they had yet to face the effects of the non-Israelite prophet Balaam's attempt to get round his inability to curse Israel by introducing an anti-God fertility cult to the heart of the Israelite camp in order to destroy them all — You can read about that and how Phinehas, Aaron's grandson stopped it in Numbers 25 — but Moses could have pointed back to Cain's murder of Abel and how the rebellion and the words spoken in it were expressions of nothing less than unbelief in the very face of God's provision of life and reconciliation.
Lest we should think that the message from the story told by Jude about Michael the archangel contending for the body of Moses is given to show that angels know better we had better note who it is that Michael was contending with. The rebellion of unbelief that shakes its fist in the face of God's grace and is swallowed up whole into hell itself has been Satan's from the very beginning. Michael's care in not giving as bad as he got is because Lucifer's fall could have been his.
Let us be exceedingly careful as we handle things that we don't understand because there is a principle in mankind while still at enmity to God that has us blaspheming God simply because we will not seek understanding nor put our trust in him while at the same time those leads which we instinctively follow lead us, as it were, to be still contending with God as the ground opens up and swallows us.