'Believe' in the Bible

What then? If some did not believe, their unbelief will not nullify the faithfulness of God, will it?

even the righteousness of God through faith in Jesus Christ for all those who believe; for there is no distinction;

and he received the sign of circumcision, a seal of the righteousness of the faith which he had while uncircumcised, so that he might be the father of all who believe without being circumcised, that righteousness might be credited to them,

but for our sake also, to whom it will be credited, as those who believe in Him who raised Jesus our Lord from the dead,

Now if we have died with Christ, we believe that we shall also live with Him,

that if you confess with your mouth Jesus as Lord, and believe in your heart that God raised Him from the dead, you will be saved;

How then will they call on Him in whom they have not believed? How will they believe in Him whom they have not heard? And how will they hear without a preacher?