What is the biblical basis for salvation by faith alone (sola fide)? One of the key issues in the Reformation was the doctrine of Sola Fide, that is, that salvation is by faith alone, apart from works.

What, then, is the biblical basis for this belief?
I'm going to have to limit my quotes from Scripture and leave some compelling verses out, because there are simply so many.  This answer would be even longer than my  normal long-winded answers if I included all supporting Scripture references.  Please forgive me if I miss something you consider relevant.



First, there is the entire book of Romans, which is a build-up to, statement of, and then supporting evidence of, the doctrine.  Some relevant verses:

Chapter 1 is a description of Gentiles (non-Jews) and shows the wickedness as part of the build-up.  By extension, this shows that religious affiliation (even to a so-called "one true Church" as many denominations claim) can save us.

Chapters 2 segues into showing that the Jew is no better, for even though they have the promise of God, they are still corrupt.

Chapter 3 continues to show that the Jew (and by extension everyone) is unable to attain salvation through the works of the Law and gets to verse 27:


  Romans 3:27 and 28 (KJV)
  
  27 Where is boasting then? It is excluded. By what law? of works? Nay:
  but by the law of faith.  28 Therefore we conclude that a man is
  justified by faith without the deeds of the law.


The remainder of Romans is support for this doctrinal statement.  Paul starts out by showing how the early heroes of the Jewish faith were not justified by their own goodness, but by Faith on God.

He then goes on to show how the Law is perfect, and cannot save us, but rather was given to us that we might know what sin is - so that we can realize that we are sinful.  

In the words of Ray Comfort in his teaching on Hell's Best Kept Secret, God's Law is like a mirror that shows us to ourselves in our true nature.  If we see we have a dirty face in a mirror, we don't wash our faces with the mirror.  No, we wash our faces with water.

Likewise, we can't wash away our sins with the mirror of God's law, but instead are washed clean by the blood of Christ. This is the essence of the message to the Romans.

Other verses throughout the New Testament also state this doctrine plainly.


  Epesians 2:8-9 (KJV) 8 For by grace are you saved through faith; and that not of yourselves: it is the gift of God: 9 Not of works,
  lest any man should boast.


As I said in the beginning, a comprehensive list of Scriptures would be prohibitively large, and it would be impossible to do a better job of answering this than has already been done by Paul in Romans, but here is a link to an article with more.

http://www.biblefacts.org/bible/salfaith.html