If you’re witnessing to an individual and their objection to the Bible concerning Jesus fulfilling Old Testament prophecy is that the New Testament books were written long after the death and resurrection of Jesus. It would have been easy for a people knowledgeable in the Old Testament prophecy concerning the Messiah to be certain that all of the prophecy concerning the Messiah were included. How can I help this person?
This kind of objection is easily refuted. Just about every expert agrees that almost all of the New Testament was written before the fall of Jerusalem in 70 AD. Many eye witnesses to the events the writers describe would have still been alive, and a great number of them would have been hostile, looking for anything they could find to discredit the writers’ accounts. These attempts have continued through that last 2,000 years. Because of that, the New Testament is one of the most thoroughly validated ancient writings in existence. Billions of people have staked their eternal destiny on its validity.
But the important thing to consider here is that for the most part people make decisions on the basis of emotion, and then try to support them with reasons that sound logical. This is especially true with religion. There’s no shortage of provably false information available for this purpose. But trying to refute an emotional position with logic is futile, and often serves to further polarize people.
Jesus told the disciples that if anyone did not receive them and listen to them to shake the dust off their feet and move on as a testimony against them (Mark 6:11).
If you’ve explained the basics of the Gospel you’ve done all that the Lord has asked of you. Now the best thing to do is pray that the Holy Spirit will open his heart to receive the Lord.