Really good question Davs ,
capnator cited the prime text , God permitting I'll expound a bit .
So then faith comes by hearing, and hearing by the word of God. <-----> Romans 10:17
And by hearing it is meant understanding also .... else we be as those of whom it is said -
And in them is fulfilled the prophecy of Isaiah, which says, By hearing ye shall hear, and shall not understand; and seeing ye shall see, and shall not perceive: <-----> Mathew 13:14
As far as where does faith come from ? Well everything originates from God through His Word / Son / Spirit .
The hearing ear, and the seeing eye, the LORD hath made even both of them. <-----> Proverbs 20:12
Do not err, my beloved brethren.
Every good gift and every perfect gift is from above, and comes down from the Father of lights, with whom is no variableness, neither shadow of turning. <-----> James 1:16+17
For who makes thee to differ from another? and what hast thou that thou did not receive? now if thou did receive it, why dost thou glory, as if thou had not received it? <-----> 1st Corinthians 4:7
The LORD hath made all things for himself: yea, even the wicked for the day of evil. <-----> Proverbs 16:4
Thou art worthy, O Lord, to receive glory and honor and power: for thou hast created all things, and for thy pleasure they are and were created. <-----> Revelation 4:11
But this is not to suggest a fatalistic approach ( where everything is whatever it will be regardless of what we do ) , for a sizable part of what God gives us is the inspiration to -
... Work out [our] own salvation with fear and trembling. <---> From Philippians 2:12
For that is an integral aspect of being " in God's image " .
But back to faith - simply put , faith is the ability to act with the assurance that comes from knowing what pleases The Lord through understanding God's will , ( which is explicitly conveyed by His Word ).
For example - If one understands that God is pleased by those who function as peacemakers , then one can act according to peacemaking ways with the faith / assurance that God will be with them both assisting and supporting them and their efforts.
Blessed are the peacemakers: for they shall be called the children of God. <-----> Matthew 5:9
Let us therefore follow after the things which make for peace, and things wherewith one may edify another. <-----> Romans 14:19
And ... If God be for us, who can be against us? <---> Romans 8:31
Once we understand from God's word , and apply this understanding - faith wells up from within by the virtue of the truth , specifically regarding what it is that we need to be pursuing , and how it is that we are to be behaving in order to be pleasing in God's sight , and thereby be in a position to be favored and blessed in a much greater capacity than we ever could have been while being in a state of ignorance and confusion . Yes , it is hearing and understanding God's Word which enlightens us so that we no longer walk in that darkness where everything is doubtful .
Moreover , this enlightenment which enables faith is not the end of our spiritual quest , yea , it is only the beginning : for now our faith need be applied , and tried , and refined , so that we grow up unto the full potential which God has provided for us in Jesus .
Beloved, think it not strange concerning the fiery trial which is to try you, as though some strange thing happened unto you:
But rejoice, inasmuch as ye are partakers of Christ's sufferings; that, when his glory shall be revealed, ye may be glad also with exceeding joy. <-----> 1st Peter 4:12+13
That the trial of your faith, being much more precious than of gold that perishes, though it be tried with fire, might be found unto praise and honor and glory at the appearing of Jesus Christ: <-----> 1st Peter 1:7
Wherefore be ye not unwise, but understanding what the will of the Lord is. <-----> Ephesians 5:17
Furthermore then we beseech you, brethren, and exhort you by the Lord Jesus, that as ye have received of us how ye ought to walk and to please God, so ye would abound more and more. <-----> 1st Thessalonians 4:1
Finally , it worth considering that faith is likened to a mustard seed ( a very small seed ) but which grows to be a large plant - this conveys the fact that faith begins in a small way , but when it is sown in a " good and honest heart " , where it will be watered and shone upon regularly by God's Word & Spirit , it is certain to grow strong - even to the point where mountains will move and seas part in the face of the great faith which comes from understanding and being aligned with God's Divine Will for us in Jesus Christ .
Thanks be to our Lord and Saviour . Amen .
wm