Jesus showed from Scripture that the Sadducees were wrong in ridiculing the idea of life after death.

Mark 12:18-27

18 Men who belong to the Sadducee sect deny that people become alive again after they die. In order to discredit Jesus by ridiculing the idea that people will live again, some of them came to him and asked him, 19 “Teacher, Moses wrote for us Jews that if a man who has no children dies, his brother should marry the dead man’s widow. Then if those two bear children, everyone will consider that those children are the children of the man who died, and in that way the dead man will continue to have descendants. 20 So here is an example. There were seven boys in one family. The oldest one married a woman, but he and his wife did not bear any children. Then he later died. 21 The second brother followed this law and married that woman and he, too, did not bear any children. Then he later died. The third brother did like his other brothers did. But he also did not bear any children, and later died. 22 Eventually all seven brothers married that woman, one by one, but they had no children, and one by one they died. Afterwards the woman died, too. 23 Therefore, if it were true what some people say, that people will become alive again after they die, whose wife do you think that woman will be when people become alive again? ◄Keep in mind that she was married to all seven brothers!/She was married to all seven brothers, so how can anyone decide [RHQ]?►” 24 Jesus replied to them, “You are certainly wrong [RHQ]. You do not know what they have written in the Scriptures about this. You also do not understand God’s power to make people alive again. 25 That woman will not be the wife of any of them, because when people have become alive again, instead of men having wives and women having husbands, they will be like the angels in heaven, who do not marry. 26 But as to people becoming alive again after they die, in the book that Moses wrote, he said something about people who have died that I am sure that you have read [RHQ]. When Moses was looking at the bush that was burning, God said to him, ‘I am the God whom Abraham worships and the God whom Isaac worships and the God whom Jacob worships.’ 27 It is not dead people who worship God. It is living people who worship him. Abraham, Isaac and Jacob died long before Moses lived, but God said that they were still worshipping him, so we know their spirits were still alive! So your claim that dead people do not become alive again is very wrong.”