23 The same day the Sadducees, who say there is no resurrection, came to Him and asked Him,
24 saying: “Teacher, Moses said that if a man dies, having no children, his brother shall marry his wife and raise up offspring for his brother.
25 Now there were with us seven brothers. The first died after he had married, and having no offspring, left his wife to his brother.
26 Likewise the second also, and the third, even to the seventh.
27 Last of all the woman died also.
28 Therefore, in the resurrection, whose wife of the seven will she be? For they all had her.”
29 Jesus answered and said to them, “You are mistaken, not knowing the Scriptures nor the power of God.
30 For in the resurrection they neither marry nor are given in marriage, but are like angels of God in heaven.
31 But concerning the resurrection of the dead, have you not read what was spoken to you by God, saying,
32 ‘I am the God of Abraham, the God of Isaac, and the God of Jacob’? God is not the God of the dead, but of the living.”
33 And when the multitudes heard this, they were astonished at His teaching.
This account is also found in Mark 12:18-27 and Luke 20:27-38.
The Sadducees did not believe in the resurrection — their question reflected this belief by attempting to mock it. The only accepted the Torah (Genesis to Deuteronomy).
The Sadducees were Nationalists and did not believe in angels or any invisible powers, nor in the resurrection. Their main dispute with the Pharisees was as to whether the oral tradition was binding. The Pharisees held it of equal value with the written law; the Sadducees said that everything not written might be rejected or was at least open to question. They considered the doctrine of the resurrection a mere matter of pious opinion. They said the doctrine was without authority in the written law, especially since, in their opinion, the prophets were not of equal value with the Pentateuch.
Christ showed that those who professed reverence for the law and showed their respect for it by quoting it on this occasion were really ignorant of what the law taught. Jesus quoted what God had said to Moses: “I am the God of Abraham, the God of Isaac, and the God of Jacob” (Matthew 22:32). The force of Christ’s argument turned on the present tense of the verb “I am.” God should have said, “I was,” if Abraham, Isaac, and Jacob had died, and were now dead, and there was no resurrection. But since God said, “I am” the God of Abraham, Isaac, and Jacob, He was testifying to their existence and the ultimate resurrection of their bodies. There could be no doubt but that Abraham, Isaac, and Jacob had died physically when God spoke these words to Moses. But God’s words indicated that they were alive and that there would be a bodily resurrection. Christ not only affirmed the fact of resurrection but indicated something of the nature of life in resurrection when He said, “People will neither marry nor be given in marriage; they will be like the angels in heaven” (Matthew 22:30). This statement was designed to refute the false concept of the Sadducees concerning the nature of life in resurrection that led them to repudiate the doctrine. — Pentecost, page 389.
Moses said (v.24) — Deuteronomy 25:5 — If brothers dwell together, and one of them dies and has no son, the widow of the dead man shall not be married to a stranger outside the family; her husband’s brother shall go in to her, take her as his wife, and perform the duty of a husband’s brother to her.
like angels (v.30) — a glorified body incapable of reproduction or destruction
The quote in verse 32 is from Exodus 3:6.