Luke 18:20
Keep the commandments
to inherit eternal life

The context of this verse, which has five imperatives, is that a certain ruler asks Jesus what he must do to 'inherit eternal life'. Jesus answers this question by giving what seems to be a summary of the law. There are four things Jesus told him not do (adultery, murder, stealing, giving false testimony), and one thing he should do (honor your parents).

So if the ruler would keep these commandments, he would 'inherit eternal life'. But wait a minute. Does Christianity not teach that faith in Jesus gives eternal life? Why then does Jesus teach here that not committing certain sins and honoring your parents results in inheriting eternal life?

It gets more interesting. The ruler states that he has kept these commandments all his life. Jesus does not contradict this statement so it was probably true. But He does say that the ruler still lacks one thing. He should sell all that he has and give it to the poor, so that he will have treasure in heaven. Then he should follow Jesus. So Jesus asks him to give up the thing he values most in this life, so that he will gain a treasure in the next. Sadly, the ruler could not do it, because he was very wealthy.

The ruler was a Jew who lived in Jesus' days. As such, his sins were already covered by the annual 'day of atonement' sacrifice. So he is probably not asking if he is going to live (as in breath) forever. Eternal life is often better translated as 'dominion in the age' (see section 2.4 in this study guide for a full explanation). And in the NT, inheritance can be earned as a reward (Col 3:23 "you will receive an inheritance from the Lord as a reward"). So the ruler is asking what to do in order to get a better position in the next life, how to get an eternal reward. Jesus tells him exactly what to do. Obey the commandments and become a disciple.

The principle is the same for us. If we want to lay up treasure in heaven (which is obviously possible), then we should keep the commandments, and become a disciple. A disciple is someone who is willing to give up everything in order to follow Jesus. A good question to ask yourself is this: If God would want you to give up all your money, or your job, or your health, or leave your family, in order to follow him, would you be willing and able to do it?

The cost of discipleship is high, but so are the rewards.