Notice a progressive heightening of thoughts through verses 2-4: “faith” in withstanding the “test” produces “steadfastness,” which in turn makes the higher goals of “perfection” and “completeness” possible.

Verse 4 consists of two clauses in Greek; the first is an imperative, and the second a final purpose clause that is grammatically dependent on the imperative clause, but in thought parallel to it. The meaning of the phrase full effect can be understood as letting “endurance” develop fully and completely until it produces “full and perfect steadfastness.” It is best, however, to take it in the sense of letting steadfastness lead on to its “proper and full effect.” This is the sense favored by most modern translations; for example, “steadfastness must have full play” (Goodspeed), “until that endurance is fully developed” (Phillips [Phillips]), “this ability must go right on to the end” (Barclay), “perseverance must complete its work” (New Jerusalem Bible). In English let … have does not convey the imperative force that is in the Greek original. The New English Bible rendering that is cast in the conditional mood (“and if you give fortitude full play”) has certainly missed the force. And so most translators prefer to use the word “must.” The Good News Translation restructuring brings out the force most effectively, “Make sure that your endurance carries you all the way,” adding “without failing.” Other alternative translation models may be “Make sure that your ability to endure does not stop [or, does not become weak],” “Make sure that your heart [or, liver] endures without ever giving up,” or “Make sure that your heart endures and gets as strong as possible.” We may also follow the Contemporary English Version rendering, “But you must learn to endure everything.”

The purpose of letting the quality of steadfastness have its full effect is to grow and produce higher qualities, that you may be perfect and complete. The Greek word for perfect is a favorite term in this letter. It appears again in 1.17, 25; 2.22 (“completed”); and 3.2. The word generally means “that which is perfect” when referring to things, or “full-grown” or “mature” when used of persons. It can also mean “perfect,” or “fully developed,” or “complete goodness” in the moral sense. It always points to an end or goal. In the New Testament it often means a maturity of character that God wants Christians to attain (compare 1 Cor 2.6; Eph 4.13; Phil 3.15). The word complete means literally “whole in all its parts.” It occurs elsewhere in the New Testament only in 1 Thes 5.23, where RSV renders it “kept sound,” and Good News Translation “whole being.” Since the word is often used in pairing with the word perfect, it naturally acquires a moral or ethical sense of “blameless.” It is clear from the context that both terms are related to moral integrity (for example, “men of mature character, men of integrity” (Phillips). The focus of perfect may be on attaining maturity of character, while the focus of complete is on being free from defect. It is, however, unnecessary to separate the significance of the two words. Some translations have therefore understood this “and” construction as referring to a single idea of perfection; for example, “go on to complete a balanced character” (New English Bible), “so that you may be fully mature” (New American Bible [New American Bible] 1970), and “so that you may be completely mature” (Contemporary English Version). In many languages this will be the more natural way to render these two terms; for example, “that you may be good in every way,” or “that you may become a completely good person.”

The phrase lacking in nothing is best taken as an added explanation of the quality just mentioned, not as another quality to be attained. The word lacking is used of the defeat of an army, giving up without a struggle. It means falling short of a standard. Taken with the previous expression it can be rendered in various ways; for example, “… men of integrity with no weak spots” (Phillips), “… a balanced character that will fall short of nothing” (New English Bible), “… complete, and not fail in any way” (Translator’s New Testament), “… complete, not deficient in any way” (New Jerusalem Bible).

An alternative translation model for this verse may be:
• Make sure that your ability to endure grows as strong as possible, so that you may become a completely good person with no defects at all.

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 .