In the synoptic gospels, there is an instance described that baffles modern Christians. A rich young ruler approaches Jesus, asks what he has to do to be saved, Jesus tells him to follow the commandments, and follows that up with a command to sell all he has and give to the poor, because:

Mar 10:25 It is easier for a camel to go through the eye of a needle than for a rich man to enter the kingdom of God.”

This scares modern Christians for several reasons. Bart Ehrman, in his book Jesus: Apocalyptic Prophet Of The New Millennium, touches on a few:

Ever since, readers of the story have gone away crestfallen as well, especially those who suspect that Jesus meant what he said, and that his injunction wasn’t limited to this one particular fellow. Interpreters have tried to get around the problem since it was first written (especially interpreters who weren’t willing to give away everything for the coming Kingdom); but doing so ignores its logic. Everyone who saves his life will lose it. Jesus’ demands were simple, in that they weren’t that difficult to figure out; but they were also radical. The Kingdom required an absolute commitment. No one should look for it without considering what it would cost (cf. Luke 14:28-33)—for it will cost everything.

But a contextual understanding, Bart Ehrman points out, will show Jesus was preaching an imminent coming of the Kingdom of God. People were to sell all they had, because as in Acts 2, everyone was expecting the end to come quickly. Ehrman explains:

That’s why, for Jesus, the present life holds no real attractions. Life in the present age should be at best a matter of indifference. One shouldn’t be concerned about such trivial matters as what kind of clothes to wear or what kind of food to eat. As he says in the Q source, “seek first the Kingdom of God, and all its right way of living, and all these things will be added to you” (Matt. 6:33). What does its “right way of living” entail? It entails loving God, the one who brings the Kingdom, and one’s neighbor as oneself. All else should be completely secondary in importance. If thieves want to take your clothes—let them! If bullies want to force you to do their work for them—let them! If the government wants to take your money—let them! If thugs want to beat you— let them! If enemies want to kill you—let them! None of these things matters. You should give away your shirt as well as your coat, you should go an extra mile, you should render unto Caesar the things that are Caesar’s, you should turn the other cheek, you should not fear the one who can destroy your paltry body. The Kingdom is coming, and the concerns of this life are trivial by comparison (see Matt. 5:39-42; 10:28; Mark12:17; Luke 6:29-30; 12:4-5).

This is made clear by the context of the passages:

Mar 10:29 So Jesus answered and said, “Assuredly, I say to you, there is no one who has left house or brothers or sisters or father or mother or wife or children or lands, for My sake and the gospel’s,
Mar 10:30 who shall not receive a hundredfold now in this time—houses and brothers and sisters and mothers and children and lands, with persecutions—and in the age to come, eternal life.
Mar 10:31 But many who are first will be last, and the last first.”

Notice that Jesus promises rewards “in this time”. These are physical rewards, family, houses and lands. Jesus taught an imminent coming of a physical kingdom that would give the righteous rewards, and that is why people were told to sell everything they had. If people sell everything they have without the Kingdom of God coming to earth, they end up like the Saints in Jerusalem (Acts 2) who had to rely on charity to survive (1Co 16).