Mar 16:15 And he said unto them, Go ye into all the world, and preach the gospel to every creature.
Mar 16:16 He that believeth and is baptized shall be saved; but he that believeth not shall be damned.
Gal 3:26 For ye are all the children of God by faith in Christ Jesus.
Your question was “How do we obtain spiritual faith?
If we hear not the Gospel preached unto us then how is that faith comes? The beginning of our faith comes with believing that Jesus Christ is the Son of God, was crucified for our sins, raised the third day, and now sits on the right hand of the power of God. And this is done by those who preach the Word to those who are lost.
If it does not come by hearing the Word, than where pray tell where does it come from?
In Christ, 1Christianwarrior316