Ecclesiastes 9:5 (NASB):
5 For the living know that they will die; but the dead do not know anything, nor do they have a reward any longer, for their memory is forgotten.
Mark 12:26-27 (NASB):
26 But regarding the fact that the dead rise, have you not read in the book of Moses, in the passage about the burning bush, how God spoke to him, saying, ‘I am the God of Abraham, the God of Isaac, and the God of Jacob’? 27 He is not the God of the dead, but of the living; you are greatly mistaken.”
Ecclesiastes 9:5 says that those who have passed away know nothing (as if they were asleep/unconscious). However, Jesus' statements in Mark 12:26-27 give the impression that Abraham, Isaac and Jacob are not truly dead, but alive (somewhere else? in a temporal paradise? in Heaven?). But if they are living, then the first sentence of Ecclesiastes 9:5 would apply instead (for the living know they will die), which would make no sense either. In other words, it's not very clear to me what is meant by "living" and "dead" in these contexts, and I would appreciate some help in making sense of and harmonizing these two passages.