Jesus rebukes the Sadducees because they are mistaken about God's law. This may be written as a statement. AT: "You are mistaken because ... power of God." (See: [[rc://en/ta/man/translate/figs-rquestion]])
# you do not know the scriptures
This means that they do not understand what is written in the Old Testament scriptures.
# the power of God
"how powerful God is"
# For when they rise
Here the word "they" refers to the brothers and the woman from the example.
Waking and getting up from sleep is a metaphor for becoming alive after having been dead. (See: [[rc://en/ta/man/translate/figs-metaphor]])
# from the dead
From among all those who have died. This expression describes all dead people together in the underworld. To rise from among them speaks of becoming alive again.