23 The same day Sadducees came to him, who say that there is no resurrection, and they asked him a question, 24 saying, “Teacher, Moses said, ‘If a man dies having no children, his brother must marry the widow and raise up offspring for his brother.’ 25 Now there were seven brothers among us. The first married and died, and having no offspring left his wife to his brother. 26 So too the second and third, down to the seventh. 27 After them all, the woman died. 28 In the resurrection, therefore, of the seven, whose wife will she be? For they all had her.”
29 But Jesus answered them, “You are wrong, because you know neither the Scriptures nor the power of God. 30 For in the resurrection they neither marry nor are given in marriage, but are like angels in heaven. 31 And as for the resurrection of the dead, have you not read what was said to you by God: 32 ‘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.” 33 And when the crowd heard it, they were astonished at his teaching. Matthew 22: 23-33 ESV
Matthew 22: 23-33
The same day Sadducees came to Him - These were a sect of very liberal, "modernist" Jews, who would have also sat opposite the Pharisees in most discussions politically and morally. They had watched their more conservative counterparts get shot down in discussions with Jesus, but now they feel they have something to ad to these conversations.
Judaism in the first century was not a monolithic movement. Certainly, beliefs such as monotheism united the Jews, but there was a diversity of Jewish sects, each having its own emphases. Politically, one might be a Zealot and advocate the overthrow of Rome's rule over the Holy Land by any means necessary, or one might be a Herodian and support Herod's dynasty, which Rome set over the Jews as their nominal head. Theologically, a Jewish person could join the Essenes, a monastic sect that advocated withdrawal from society to a life of purity in the wilderness. Or, a Jew could follow the Pharisees, who kept the oral traditions of the rabbis, stressed divine sovereignty, and affirmed the resurrection of the dead.
Today, as we return to our study of Mark's gospel, we find the Sadducees, a first-century Jewish sect that stressed the power of our free will and who believed theology could be based only on the five books of Moses (Genesis–Deuteronomy). As a consequence of this belief, the Sadducees did not believe in the resurrection of the dead, for we do not find resurrection taught explicitly in the first five books of the Bible. Yet, we do find it there implicitly, or by good and necessary consequence, as Jesus will show us in due course (Mark 12:25–27). - Ligonier.org
Who say that there is no resurrection - This was one of the key doctrinal differences of the Sadducees. So when they ask a question about the resurrection, we know they are asking about what they already don't believe, so it is more in trying to prove a point. Well, at least they thought it was clever, and in a way it would have been, except their premise was based upon assumption. The assumption is that the resurrection is to an improved version of now, and their counterparts, the yang to their yin, the Pharisees, may well have held that sort of speculation. Even atheists can't help but ponder an afterlife sometimes, but Scripture really only makes it clear that there is one, but what it is exactly like is veiled in mystery.
1“At that time Michael, the great prince who stands watch over your people, will rise up. There will be a time of distress, the likes of which will not have occurred from the beginning of nations until that time. But at that time your people—everyone whose name is found written in the book—will be delivered. 2And many who sleep in the dust of the earth will awake, some to everlasting life, but others to shame and everlasting contempt. 3Then the wise will shine like the brightness of the heavens, and those who lead many to righteousness will shine like the stars forever and ever.… Daniel 12: 1-3
1Behold what manner of love the Father has given to us, that we should be called children of God. And that is what we are! The reason the world does not know us is that it did not know Him. 2Beloved, we are now children of God, and what we will be has not yet been revealed. We know that when Christ appears, we will be like Him, for we will see Him as He is. 3And everyone who has this hope in Him purifies himself, just as Christ is pure.… 1 John 3: 1-3
His brother must marry the widow and raise up offspring for his brother - This was the custom in taking care of widows under the OT law. This gave the widow children that would keep her in her old age, but also since the children were raised up to the dead brother's name, it kept the property with the families it was allotted to as well, protecting the widows and their children.
Seven brothers...whose wife will she be - Now to them this created a dilemma, but Jesus could just have easily said, "to the first", but this was not the case. The seven was an inflated exaggeration, probably meant for humor and theatre as they tried to drive home their point, hyperbole. The real issue was they didn't believe in the resurrection, they didn't accept the writings of the prophets after Deuteronomy as canon, and they assumed that they had a proper understanding of the Pentateuch, along with the assumption that the resurrection was as they portrayed it in their narrative.
You are wrong, because you know neither the Scriptures nor the power of God - Straight up, "you are wrong", speaking to their question, and their assumptions. Your theology is bad because your doctrine is incorrect, because you don't understand the Word of God. I can just see them, like so many modern day evangelicals, enamored with the culture, "well that's your opinion, Jesus, that's your truth, but there's more than one way to interpret your Father's word."
…4traitorous, reckless, conceited, lovers of pleasure rather than lovers of God, 5having a form of godliness but denying its power. Turn away from such as these! 6They are the kind who worm their way into households and captivate vulnerable women who are weighed down with sins and led astray by various passions,… 2 Timothy 3: 4-6
For in the resurrection - Jesus believes in the resurrection, and He has been raising people from the dead. So any doubts they had about the stories of Elijah and Elisha, those resurrected in that time, or Daniel speaking of the resurrection, those "trusting the science" in Jesus' time should observe both what He affirms and the miracles He performs. Lazarus will be an incredible one because he was in the tomb till it stank. It's funny how those who acknowledge their consciousness now think it too miraculous to speak of an after life, as though this life were a given, how petty, unscientific and entitled can one be?
38Jesus, once again deeply moved, came to the tomb. It was a cave with a stone laid across the entrance. 39“Take away the stone,” Jesus said. “Lord, by now he stinks,” said Martha, the sister of the dead man. “ It has already been four days.” 40Jesus replied, “Did I not tell you that if you believed, you would see the glory of God?”…
…41So they took away the stone. Then Jesus lifted His eyes upward and said, “Father, I thank You that You have heard Me. 42 I knew that You always hear Me, but I say this for the benefit of the people standing here, so they may believe that You sent Me.” 43After Jesus had said this, He called out in a loud voice, “Lazarus, come out!”…
44The man who had been dead came out with his hands and feet bound in strips of linen, and his face wrapped in a cloth. “Unwrap him and let him go,” Jesus told them. 45Therefore many of the Jews who had come to Mary, and had seen what Jesus did, believed in Him.… John 11: 38-45
They neither marry nor are given in marriage - Now we know something about heaven from the mouth of Christ, Who descended from heaven. It was not how the Sadducees assumed about the thing they didn't believe in.
As for the resurrection of the dead, have you not read - He takes them back to the books they did believe in, and so easily too, beautiful how the Word is with Him. Even Abraham trusted the promise of God so much that he believed He would raise Isaac from the dead just to keep His word. The Sadducees weren't great students of Scripture though and Jesus demonstrates it with a verb "am".
More importantly, the Sadducees were wrong about the resurrection of the dead because Scripture proclaims that we will rise from the grave. Even the five books of Moses, the only portion of the Old Testament that the Sadducees used for their theology, teach the resurrection. Jesus pointed to Exodus 3 as proof for the resurrection, noting that God said to Moses, "I am the God of Abraham, and the God of Isaac, and the God of Jacob" (Mark 12:26–27). Implicitly, our Lord argued on the basis of both the verb tense and theology. If death ended the patriarchs' existence, God would have said, "I was the God of Abraham, Isaac, and Jacob." Our Creator's use of the present tense implies that they live on to worship Him. Moreover, the Lord always keeps His promises, and His promise to the patriarchs—long life in the Promised Land, ultimately, the new creation (Gen. 12:1– 3; Matt. 5:5)—can be ful lled only if they will live forever. - Ligonier.org