Romans 10:9-11

...if you confess with your mouth the Lord Jesus and believe in your heart that God has raised Him from the dead, you will be saved. For with the heart one believes to righteousness, and with the mouth confession is made to salvation. For the Scripture says, "Whoever believes on Him will not be put to shame."

Romans 10:14

How then shall they call on Him in whom they have not believed? And how shall they belive in Him of whom they have not heard? And how shall they hear without a preacher?

Romans 10:16-17

But they have not all obeyed the gospel. For Isaiah says, "Lord, who has believed our report?" So then faith comes by hearing, and hearing by the word of God.

Hebrews 11:6

But without faith it is impossible to please Him, for he who comes to God must believe that He is, and that He is a rewarder of those who diligently seek Him.

John 8:22-24

So the Jews said, "Will He kill Himself, because He says, 'Where I go you cannot come'?" And He said to them, "You are from beneath; I am from above. You are of this world; I am not of this world. Therefore I said to you that you will die in your sins; for if you do not believe that I am He, you will die in your sins."

I Corinthians 15:1-2

Moreover, brethren, I declare to you the gospel which I preached to you, which also you received, and in which you stand, by which you also are saved, if you hold fast that word which I preached to you--unless you believed in vain.