The same day Sadducees came to him, who say that there is no resurrection, and they asked him a question,  saying, "Teacher, Moses said, 'If a man dies having no children, his brother must marry the widow and raise up children for his brother.'  Now there were seven brothers among us. The first married and died, and having no children left his wife to his brother.  So too the second and third, down to the seventh.  After them all, the woman died.  In the resurrection, therefore, of the seven, whose wife will she be? For they all had her."
 But Jesus answered them, "You are wrong, because you know neither the Scriptures nor the power of God.  For in the resurrection they neither marry nor are given in marriage, but are like angels in heaven.  And as for the resurrection of the dead, have you not read what was said to you by God:  'I am the God of Abraham, and the God of Isaac, and the God of Jacob'? He is not God of the dead, but of the living."  And when the crowd heard it, they were astonished at his teaching. Matthew 22:23-33 (ESV)
He is not God of the dead but of the living. There is today much confusion regarding the resurrection. Perhaps, somewhat because of this passage that says we will be like the angels in heaven. Or perhaps because of the inherent Platonism in western society. Perhaps because we’ve translated the Nicene Creed to say the resurrection of the body, rather than the technically more accurate flesh. Being like angels does not mean we will be angels, or bodyless beings. It means we aren’t married or given into marriage. But being resurrected isn’t about going to heaven in spirit, or our souls leaving our bodies behind.
All one has to do to understand what eternal life and the resurrection is all about is look to Jesus Christ and his resurrection, the first fruits. He was raised in the flesh, that’s the controversy, he did not appear as a ghost, but his body left the tomb. Thomas inserted his hand in the flesh.
But he is the God of the living, not of the dead. Jesus says this in order to prove to the Sadducees that there is a resurrection. The Sadducees are silenced. But this has far reaching implications. It means that Abraham, Isaac, and Jacob are not dead. That they are living depends on the fact that there is a resurrection. If there was no resurrection then one could not say that they are living.
But there is some question as to in what sense Abraham, Isaac, and Jacob are living, and what that means for us, or our loved ones who have passed on. One wonders if they are considered living in anticipation of the resurrection that is strictly a future event, or if even right now, do to the eternal nature of heaven they already enjoy their glorified bodies in heaven. I get a headache trying to think of how all that works out. One can think on these things for a long time. It is part of the beauty of Christianity I think, that in essence it is so simple a child can believe and have salvation, and yet a genius can put his brain to work on it for a life time and never plumb the depths of it.