So faith by itself …: James now draws the conclusion from the comparison. He does this by using the word So, making the application of the example. So here has the force of “In the same way” (New International Version, New Jerusalem Bible). Here the word faith refers back to the so-called “faith” in verse 14. There is some ambiguity in the expression by itself. Does it qualify faith or dead? The position of the Greek makes either a possibility. American Standard Version takes it with dead, thus “is dead in itself.” It is more probable that the phrase is placed at the end for emphasis but is intended to be taken with faith, thus “faith alone” (King James Version), or faith by itself (Revised Standard Version; so also New Revised Standard Version and many others). In this case the clause if it has no works is to be understood as an amplification of by itself.

From the conditional clause if it has no works, it is obvious that works are not something added as extra to faith—they go together. There is no intention to have a contrast between “faith” and “works”; the real contrast is between “faith that has works” and “faith that has no works.” For James faith must be accompanied by deeds; one cannot exist without the other, for the faith that does not have works is dead. Here the word dead is used figuratively to mean “lifeless,” “inactive,” and “useless.” In a number of languages it will be necessary to say something like the following: “your belief is useless” or “believing like that will be of no use [or, gain you nothing].” The conclusion explains that the faith of the professed Christian who extends best wishes to the needy brother and sister without offering practical help is worthless; it is a dead faith.

An alternative translation model for this verse may be:
• So if you only believe and don’t do good deeds, your believing is useless [or, will gain you nothing].

Quoted with permission from Loh, I-Jin and Hatton, Howard A. A Handbook on The Letter from James. (UBS Handbook Series). New York: UBS, 1997. For this and other handbooks for translators see here .