The presence of unbelievers amongst the people of God as well as their subsequent judgment is attested to throughout Scripture (Jude 1:5–7). Jude is thus not referring to a specific example but rather to the fact that these individuals are marked out for judgment. His emphasis is not on doom being predicted but on it being decreed and announced.1
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.