Here’s one reason among many: Bible prophecy.
“The stone which the builders refused is become the head stone of the corner.” Psalm 118:22.
How did the Psalmist know hundreds of years in advance that the Jewish people would reject Him when He got here? It’s not like the Jewish folks are doing it to make the Bible seem true. If they were doing it on purpose, they would have to acknowledge that Jesus is the Christ eventually, and most of them flat-out refuse. They don’t want anything to do with Jesus. They are waiting on pins and needles for their Messiah to come in and set up an earthly government, yet, if they have read their own scriptures, penned by their own people, authored by their own God, you would think it might occur to them that He would have to first be rejected.
Also, how can they look for a kingdom to last forever when they have this prophecy: “And after threescore and two weeks shall Messiah be cut off, but not for himself:” Daniel 9:26 Are they wanting Him to come in, set up a kingdom, and THEN be cut off? That doesn’t make an ounce of sense. In fact, I have discovered through research that the Jews long believed that there would be two Messiahs. It was the only way they could reconcile the fact that He was prophesied to suffer and die for us (Isaiah 53 – which they used to acknowledge was about Him, but deny it now), and also prophesied to establish an eternal kingdom on the earth. Now they refuse Jesus on the basis that He didn’t fulfill ALL of the prophecies and therefore can not be the Messiah. They should really look into their own religion a little more and see what changed in rabbinical thinking and literature AFTER Jesus came and fulfilled the first part of the prophecies. The changes are quite telling.
Their own prophecies only make sense in the light of the birth, life, death, burial, resurrection, and return of Yeshua Messiah. He fulfilled the prophecies in a way that they couldn’t have fathomed, much less predicted.
In general, I have found that modern Christendom is pretty inadequate at giving any proof that Jesus is the Christ because many believers refuse to comb the Old Testament. Many will say – “you just have to have faith.” And I do believe that God gives us all the measure of faith we need to believe, but it kind of upsets me that we have such a body of evidence that we are completely neglecting, especially in light of Luke’s treatise that he gave to Theophilus (which word I think breaks down into “lover of God” in Greek). He says he gave it to us “That thou mightest know the certainty of those things, wherein thou hast been instructed.” Luke 1:4 This book was written with the care and scholarship of an educated man, a man who didn’t expect people to believe him just because he said so, a man dedicated to presenting the truth in a manner that could be confirmed by anyone who chose to look into the facts. The book of Acts was written in the same fashion, also authored by Luke. It should come as no surprise then, that Luke quotes from the Old Testament A LOT throughout both books, giving the proof that Jesus is exactly who He says He is.
The proof that God exists is found in the perfect harmony between the Old Testament and the New – in the continual and perfect foreshadowing of an event that nobody ever saw coming. In fact, I have not found a single New Testament doctrine that wasn’t foreshadowed in the Old. Everything from baptism to the final trumpet blast is represented in the OT. Even the mystery of the gospel, which has to do with the salvation of the Gentiles.
And why make it a mystery? Why keep everything a secret, continually foreshadowing but explaining nothing? “…we speak of the mysterious and hidden wisdom of God, which He destined for our glory before time began. None of the rulers of this age understood it. For if they had, they would not have crucified the Lord of glory.” 1 Corinthians 2:7-8. Also, for you, Seeker, so that you will know that something that marvelous couldn’t have been mysteriously hinted at countless times, yet come to pass in a way that ties up every loose end, answers every riddle, laughs in the face of coincidence.
I’m not finished looking yet, but I am beginning to suspect that everything the New Testament teaches has its foundation in the Old. We know that everything Paul taught originated with the Old: “Having therefore obtained help of God, I continue unto this day, witnessing both to small and great, saying none other things than those which the prophets and Moses did say should come: That Christ should suffer, and that he should be the first that should rise from the dead, and should shew light unto the people, and to the Gentiles.” Acts 26:22-23.
God gave us brains for a purpose; He gave us logic and reasoning skills. He wants us to use them and encourage others to do the same. Believing something just because mommy said so or because society says so is a cop-out for someone who doesn’t want to take the time or make the effort to do any real research. “Study to shew thyself approved unto God, a workman that needeth not to be ashamed, rightly dividing the word of truth.” 2 Timothy 2:15. And of course, after you accept Him, you will know beyond the shadow of a doubt because “The Spirit itself beareth witness with our spirit, that we are the children of God:” Romans 8:16.
These things may not mean anything to folks who have already made up their minds about God, but it may speak to someone who is searching. I have many more scriptures to share from the OT that were amazingly fulfilled by Christ.