The massive misunderstanding of this fundamental truth has been the spiritual undoing of very many.
The believing of justifying faith is essentially juxtaposed to any work or deed or act of man, which the confused and/or dishonest maintain is part of believing. This group of people hold that a work or deed or act of man is an outside observance and in the context of justification is necessary for salvation. Some maintain that works should be required instead of a work and some call such work(s) fruit(s), but changing the name does not change the reality of the nature considered.
True believing is a passive state that cannot be seen like a work can be seen. When someone believes, he cannot be observed as having done or performed anything. Believing is within. It is created by the grace of God. It alone is acceptable before God for justification of life. Works (or even one work) cut off the person from God who so seeks justification because that condition does not believe the revelation, love, and power of God.
The life of holiness which follows true justification has always been misunderstood by those who maintain that any part of it justifies for salvation. God's love and our believing in His providing love (Jesus' atoning death upon the cross under Pontius Pilate) is the sole ground for justification for eternal life.
Consider this exact analogy of the two different conditions.
Person 1 is sitting in a chair. He is told that a former convict has changed his ways. He believes the testimony. He did nothing but believe.
Person 2 is sitting in a chair. He is told that a former convict has changed his ways. He believes the testimony, but, as part and parcel of his believing he must rise from the chair. He performs an act (standing up) as essential to believing.
Person 1 illustrates justifying faith acceptable with and approved by God.
Person 2 illustrates “justifying faith” acceptable with men and disapproved by God.