Luke 16:29 Abraham saith unto him, They have Moses and the prophets; let them hear them.
In this passage, Abraham was addressing the rich man who died and went to Hell. The rich man wanted Abraham to send Lazarus back to testify to the rich man’s five brothers so they would know that Hell is real and how to escape damnation. Abraham told the rich man that they already have what they need to know: Moses and the prophets. The prophets made many and various prophecies that have been fulfilled. The purpose of these fulfilled prophecies was so that men could have confidence in God’s word. The prophets are an appeal to our intellect. Moses represents the law – more specifically, the Ten Commandments. Moses – the law – is an appeal to our conscience.
Abraham told the rich man that all anyone needs to be saved is the law to appeal to our conscience – to convict us of our sins, to show us we are guilty before God – and the fulfilled prophecies to appeal to our intellect – to give us confidence in the word of God, to show us that the Bible is true.
If you want to win someone to Christ, you need to give them the prophets and show how the prophecies have been fulfilled so that the person will be able to believe God’s word. Then you need to throw the book at them – give them Moses and the law until they collapse under the weight and guilt of the law. Only then – when the person believes God’s word and sees themselves guilty and condemned before a holy and just God – and only then will that person be ready for the grace of God. That’s when we tell them about the Lord Jesus Christ and how he paid the penalty for us.