A - Thanks for the question. The Catholic Church teaches that the idea of "faith alone" (aka - sola fide) is incompatible with both biblical and theological evidence. We need to define what faith alone is in order to be able to understand where the Catholic Church stands.
Faith Alone is one of the basic tenets of the Protestant Reformation. Martin Luther is the father of this idea. You could call it the doctrine of justification by faith. The basics are that humanity is saved by God's grace which comes by the believer's faith alone and not by any good works that one may do.
How the Catholic Church would understand this belief depends somewhat on how the word "faith" is defined. In the bible, faith is used in many different ways. We can see this in the following verses:
For in Christ Jesus, neither circumcision nor uncircumcision counts for anything, but only faith working through love. - Gal 5:6Notice that faith must do love here. But, in Romans 14 it is much different. It starts and ends with these verses:
Welcome anyone who is weak in faith, but not for disputes over opinions. - Rom 14:1This kind of faith is found in one that has an intellectual belief in Christ.
Keep the faith (that) you have to yourself in the presence of God; blessed is the one who does not condemn himself for what he approves. But whoever has doubts is condemned if he eats, because this is not from faith; for whatever is not from faith is sin. - Rom 14:22-23
We also find verses that talk about "the faith" as a body of beliefs that we hold. One example:
I now feel a need to write to encourage you to contend for the faith that was once for all handed down to the holy ones. - Jude 3The Catholic Church does not believe that faith alone is a complete view of salvation or justification, when the faith is defined as merely an intellectual knowledge of Jesus. This is because we would have to define faith as something that is incomplete. But, most protestants do not define faith in this way. So, the common understanding of faith would include a definition that is closer to our understanding of faith, hope, and charity combined. So, in this difference of definitions is a great deal of our differences. This is why the Catholic Church and the Lutheran World Federation could issue a joint declaration on justification several years ago. This is one part of that declaration:
25.We confess together that sinners are justified by faith in the saving action of God in Christ. By the action of the Holy Spirit in baptism, they are granted the gift of salvation, which lays the basis for the whole Christian life. They place their trust in God's gracious promise by justifying faith, which includes hope in God and love for him. Such a faith is active in love and thus the Christian cannot and should not remain without works. But whatever in the justified precedes or follows the free gift of faith is neither the basis of justification nor merits it.
See how a person is justified by works and not by faith alone. - James 2:24