One of Luke's major concerns is to show that the work, passion, crucifixion, and resurrection of Jesus are the fulfillment of the Jewish scriptures (i.e., Moses, the prophets, and the Psalms). This is Luke's main way of coming to terms with the fact that Jesus—the Messiah, for crying out loud—gets crucified. God's will has been accomplished precisely through and in spite of all of those acts of opposition, betrayal, and rejection.
It's a pretty hefty concept of divine fate, necessity, determination, or even destiny. And the pesky conundrum arises: are the people who betrayed, rejected, and condemned Jesus responsible for their actions? One thing's certain. Within Luke's text they are held responsible and their punishment is expected (Judas is a case in point; see 22:22). But it's a tough line. Work through the texts for yourself and see if you can toe it.
Questions About Fate and Free Will
Which of the Jewish scriptures in particular are the sources for knowledge about fate?
At what point in the story do the disciples finally understand that God has predetermined certain events and that the authors of the Jewish scriptures have written of them beforehand?
How much scope is given to free will in Luke? And what can it possibly mean for humans to be free in light of such a hefty concept of divine necessity? It's a toughie, we know.