James 2:14-17

When someone claims to have faith, what he or she may have is intellectual assent - agreement with a set of Christian teachings - and as such it would be incomplete faith.  True faith transforms our conducts as well as our thoughts.  If our lives remain unchanged, we don't truly believe the truths we claim to believe. 

We cannot earn our salvation by serving and obeying God.  But such actions show that our commitment to God is real.  Deeds of loving service  are not substitute for, but rather a verification of our faith in Christ.

SOURCE:  Life Application Study Bible