A shocking note to anyone that has hung their theological hat on this phrase is that it is not in the Bible! In fact, the only faith that is alone in the Bible can be found in James 2:17, "Even so faith, if it have not works, is dead, being alone."
The Bible states everywhere that we are saved by faith, but it is ironic that Christians all over the world automatically insert the word "alone" where it is never put by the Holy Spirit. It is put there in many cases to contend for a dead, workless salvation.
While is is faith "alone" that saves us, we must recognize that saving faith is a faith that is not "alone." It must consist of fruit. Jesus said, "I am the vine, ye are the branches: He hat abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing. ( Jn. 15:5). "For we are his workmanship, created in Christ Jesus unto good works, which God hath before ordained that we should walk in them." (Eph. 2:10). "For it is God which worketh in you both to will and do of his good pleasure." (Phil. 2:13).
Faith works... or it is dead. A dead faith is not a saving faith.
The "faith alone" crowd has a tendency to minimize the role of works in salvation. They confuse works as a form of merit, over against the Biblical idea of works as the fruit of salvation.
Charles Stanley, Eternal Security, and the Bible