“He is not God of the dead, but of the living. You are quite wrong” (Mark 12:27, ESV)
According to Jewish law, if a man and woman married, and he died before she gave birth to an heir by him, it then became the obligation of one of that man’s brothers to marry the widow, and bring up children in his stead, carrying on the family name (Deuteronomy 25:5-10).
With that law in mind, coupled with the belief that there is no afterlife, and the possibility of trapping him in his own words, Jesus’ opponents (the Sadducees) proposed a hypothetical scenario: suppose seven good, law-abiding Jewish brothers all marry this same woman, each of them dying before she bears them a child. “In the resurrection, whose wife will she be?” (Mark 12:23).
Generally speaking, if you reduce something to an absurdity (reductio ad absurdum, if you want to sound smart) its falsehood becomes more apparent. The Sadducees believed they had constructed such an absurdity: if the afterlife involves the ridiculous, then it must be false.
The thrust of Jesus’ answer is rather insulting (to them). He said the reason the Sadducees would even propose such a question is because they ignored the Scriptures, and God (Mark 12:24).
There are many meaningful things to observe about this exchange, probably the greatest of which is how Jesus’ argument hinges on the tense of a single verb (Mark 12:26-27), but I want to take the application in a more philosophical direction.
Notice this great implication of the whole exchange: the profound value of Scripture to right thinking.
Jesus said, “The reason you are wrong [is] because you [do not] know the Scriptures” (Mark 12:24). Here’s the claim again: no man can think correctly without a proper understanding of the Bible. Fundamentalist, anyone?
We must grasp the philosophy of modern atheism/rationalism to appreciate just how offensive Jesus’ claim is. Atheists pride themselves on their powers of reason. “Freethinkers,” they call themselves. They believe that well-evolved humans (themselves) graduated from the Neanderthal caves of faith to a higher state of consciousness. Ayn Rand, for example, called religion the “default” mode of lower humans who had “not yet progressed out of it,” and that “a great many people are still in infancy” (she said this on The Tonight Show with Johnny Carson). The mighty rationalists, on the other hand, have shed the vestigial organ of religion, and they’re just waiting for (or demanding) the rest of us monkeys to come down from the trees and follow suit.
With that in mind, I hope you appreciate the profoundness of Jesus’ words. He is saying the rationalists, intelligent as they are, are wrong. They are patently wrong about reality because their assumptions and conclusions do not have a biblical basis. So far as Jesus was concerned, the rationalists are, spiritually, still in the trees and have plugged their ears full of bananas.
Jewish rabbis teach that if you know the Hebrew Scriptures, and in particular the Hebrew language, then you know reality. According to Jesus, an uneducated man who knows the Bible is in a better position to know reality than the most educated man who seeks to understand reality without it.