how can i defend the genuinity of the bible?

Is the Bible the genuine article? Is it the inspired word of God? Is there scientific proof that would convince non-believers that the Bible is indeed the word of God? The saying goes, "To the person of faith, no proof is necessary but to the non-believer, no proof is ever enough." You can speak until you are blue in the face but if a person's heart is closed to the word of God, all your words will fall off like water rolling off of a duck's back. Matters of faith are just that. That is why we call it faith. We believe even if we don't see with our own physical eyes. Do we have to open up one person's skull to prove that he or she has brain matter inside that skull? Or do we believe that there is brain matter in there because we know God created that person with a brain? How about the air that we breathe? Can we see it? Then why are we breathing air and are alive? Imagine the shock of Peter and John when they saw the empty tomb when they first peered into it? Where was Jesus? What have they done to his body? Yet they were disciples of faith and when the risen Lord appeared to them it all made sense. While it is common knowledge that the Bible was written by people, it takes faith to understand that these people were inspired by the Spirit to write down whatever they wrote down. For a non-believer this is way too much to take in - their faith system is non-existent. So their only recourse is to ask for proof. "Prove it!" There is nothing to prove. We know also that God's ways are not man's ways - the prophets told us so. Indeed, what kind of a God would God be if he were just as merely human as we are human and not divine? Tell your non-believer friends that the time will come when they will have to account for their own souls at the last judgment. They will have to stand before God and account for their own actions and the way they led their lives.

afraid i'm one of the unbelievers so not much I could say to help you

I don't think there is any scientific support because this kind of question is not examined by scientist but by historian. The test to examine the genuineness of ancient texts/books/MSS (manuscripts) is called historiography. And this comes within the branch of History. To test the genuineness of the Bible, we have to apply the test that we apply to test any other ancient MSS. And this test varies for each Manuscript. But the standard historiographical method uses three methods: bibliographical test, external evidential test and internal evidential test. If you are interested I can explain these three methods later. The test will not prove that the Bible is the word of God, but the test will prove that the biblical documents are genuine and authentic.

Ask them for scientific support to show their beliefs which I imagine is the theory of evolution. Yes there is evidence, but there are alot of gaps in the evidence which don't add up. If my friends asked why I believed what I read in the Bible I would say that it's because I believe in the trinity and I want to serve as well as I can for God by reading what he has to tell us and obey what he says. You are right in saying it's the word of God. It tells us everything we could possibly know about God so it is important for us in our religion to hear what he has to tell us.