A Right Definition of Faith

How shall we distinguish a healthy faith from one that is built on more shaky ground?  Consider this insight from John Calvin:

“Now we shall possess a right definition of faith if we call it a firm and certain knowledge of God’s benevolence toward us, founded upon the truth of the freely given promise in Christ, both revealed to our minds and sealed upon our hearts through the Holy Spirit…..

If then, we would be assured that God is pleased with and [is] kindly disposed toward us, we must fix our eyes …on Christ…  We see that our whole salvation, and all its parts, are comprehended in Christ.   We should, therefore, take care not to derive the least portion of it from anywhere else.”